Fusion Hybrid: Fuel Saving Tips and Tricks

[acdii]

I remember you saying that about the poor coasting abilities in your 13. Mine is completely different; when I take the foot of the gas it really coasts for a long time without really slowing down much at all; in CL on 14 between lights at 35 MPH I can take me foot of the gas at one traffic light when I see the next one red and still need to use the brakes when I get there.

Thats how the 10 is, but the 13, lets say I am doing 35 at Sams club and take my foot off I will have dropped 10 MPH when I reach the next light at Kmart. By the time I get halfway between that light and the next at Main, I had to give it gas to make it to the light. The only time it ever coasted was with a full charge.

 

You know, I wonder if the problem was due to the brake pedal position sensor, if it detected a slight bit of pressure it would apply regen, but it never showed up as the regen circle until I actually applied brake. This is how it acted though.

[wazzul]

I've too have noticed the aggressive drag or more likely regen when you get off the throttle above 30mph, below that it seems to coast with little drag.

[alpha754293]

Yes that's what I mean and do; foot of the gas completely. That shuts down the ICE instantly and enables the EV mode. Now I touch the has again so that the blue EV bar stays within the threshold frame.

I can usually do this with very minimal loss of speed even in hilly terrain but it's very sensitive. It was actually very hard to take the pics since I would change the has pedal position just so slightly that it would kick it into EV before I wanted or vice versa.

Now I don't know the area you are in but we have some "hills" around here too and with a little practice; a little speed loss and a decent SOC I can manage to get uphill without ICE help.

As stated by others the gas pedal is very very sensitive; the slightest change can change the power demand drastically.

 

The other thing I have tried is to reduce the power demand on the ICE while charging; I have seen 10 MPG instant display difference when you lift your foot just slightly so that the white bar stays at the first cross marker. The higher the SOC becomes the higher the instant MPGs climb just like on the interstate; "fully" charged and you can see 50+ instant MPG.

 

Actually, most of the places where I drive, the AREA that I drive is quite flat (especially around my work). The problem is that the main "throughway" street has a posted limit of 40 mph, but people routinely do 50-55 mph here. (Yeah, Michiganders drive fast nominally). And it's also 4 lanes wide. And it's also the mouth of the freeway (the street transitions right at the entrance of my work) and the freeway limit is 70 mph. So you have a street transiitioning to a freeway (40 mph => 70 mph limit; 50-55 mph => 75-80 mph in practice) and you're T-ing into it (from the parking lot).

 

So you do have to pick up speed at a decent clip otherwise, you run the risk of being rearended.

 

If it weren't for that, or if it's like after regular business hours, and assuming that the crazy racers aren't out in full force, I otherwise COULD probably stay in EV mode as much as I can while accelerating to highway speeds (69 mph/110 km/h).

 

There are SO many things that you can do between optimizing for battery SoC, having max battery, and max fuel economy; but I think that unless you do one thing constantly, all the time, every single time; it will otherwise pretty much average itself out. I have found that short time frames (upto a minute to 2 minutes); you'll see the biggest impact on your instantaneous and your local average. But if you can get to your cruising speed say in like < 5 minutes and you can hold it the rest of the way - that will probably be better for your overall economy rather than focusing on the instantaneous. You "squeeze out" the transients. Like for me - my normal commute is 24.3 km (15.1 miles), of which, 16.9 km (10.5 miles) is highway) - so getting up to cruising speed in a decent amount of time (not too fast, but not too slow either) is far better than optimizing for any one of those specific states. Let the transients ride itself out, and then let the long term (relatively speak) averaging converge on an overall trip fuel economy as opposed to chasing the transient/short-term fuel economy gains.

 

(Unless your trip is REALLY REALLY short.)

 

It depends on the roads as I've said. Here in Michigan, there are surface streets where the practical speed limit/flow of traffic is 50-65 mph and it's not all that uncommon for us to cruise like that for miles on end.

 

The only time that I really play with battery state/trying to keep it in EV mode/SoC is when I'm crossing customs. That's when I like my car to be completely silent when I'm at the booth without actually having to shut the car off. I WANT the customs agents/officers to notice how nice and quiet the hybrid is! :) That's about it though.

[acdii]

I take it in Michigan a rear ender isnt an automatic ticket like in Ill.

[alpha754293]

I take it in Michigan a rear ender isnt an automatic ticket like in Ill.

 

No. Actually, Michigan is a no-fault state, so there are a LOT of no-fault accidents. That's also why if you ever drive around the Detroit area, you see a LOT of really badly beaten up cars where the bumpers would be held by duct tape and the hood would be bungee corded (as is the trunk).

 

And it's also so sad to see that people would buy these like beautiful, brand new cars, and they can't be more than a few months old, and they're just all dented, bumped, and bruised - doesn't matter WHAT it is. It can be a Chevy and it can be a brand new Merc. Same diff from that perspective (although it's less likely on a Merc than on the Chevy, but it still happens).

[itschris]

I've had my HyTi for a couple weeks now. This is what I've figured out. I tried "chasing" the EV mode sort of like Corncobs posted above. What I found for my commute is that it tends to run the battery down which effectively gives you decreaing returns because after awhile you have to keep letting off the gas more and more unitl you have to press the gas or the engine just kicks on itself.

 

Now that may be more due to my specific commute so take it for what its worth. I drive 23 miles one way to work. Basically it's a lot stop and go. From a dead stop speed up to 30 then back to zero. I don't do that anymore. if the light ahead is red or just turned red, I just coast on up. But on the stretches where I can drive a bit, I just speed up to where I want to be let off and just keep things constant. I try not to articulate the pedal at all and just keep it steady. What I've found is that I'll suck out of EV mode, but it'll be for a short time then it kicks back in all on it's own. The interesting thing is that battery stays charged a lot more and doesn't end up going all the way dow to say an 1/8 or 1/4 full which really makes for bad efficiency in my experience.

 

Driving this way, I'm still getting the same mileage as I was chasing the EV mode, yet I have a lot more enjoyable driving experience because I can keep up with traffic and I'm not speeding up and slowing down all the time. I can actually just relax and drive.

 

I will say that sometimes the car just does better than other times on the very same commute. I can't explain it. Sometimes I'll pick up .7 or .8 avg mpg on the trip, but then days like this morning... my avg didn't change. I'm certain there are just a lot of subtle things during the drive that affect it.

[corncobs]

That exactly how I have changed my driving behavior; let the others race each other to the next light or next slower car; I keep up with traffic but I don't care if there is a gap of several cars between the car ahead and myself.

A lot more relaxing for me but it seems to be more frustrating for others like the one guy behind me this morning in his Roadmaster ready to have a heart attack not being able to chase the car in front of me.

[neod192]

That exactly how I have changed my driving behavior; let the others race each other to the next light or next slower car; I keep up with traffic but I don't care if there is a gap of several cars between the car ahead and myself.

A lot more relaxing for me but it seems to be more frustrating for others like the one guy behind me this morning in his Roadmaster ready to have a heart attack not being able to chase the car in front of me.

I had someone tailgating me this morning too. I was cruising at 35 (the speed limit) slowing down relatively slow to lights and speeding up gently (EV up to 20 MPH then constant ICE). I couldn't see this guy's hood, only his windshield. He was sooo pissed! It was a one lane road, so he couldn't pass me for like 10 minutes - we were taking the same turns and everything. When we finally got to a 2 lane road he stepped on his gas and raced by me !

 

I just laughed and kept on cruising.

[smr2112]

That exactly how I have changed my driving behavior; let the others race each other to the next light or next slower car; I keep up with traffic but I don't care if there is a gap of several cars between the car ahead and myself.

A lot more relaxing for me but it seems to be more frustrating for others like the one guy behind me this morning in his Roadmaster ready to have a heart attack not being able to chase the car in front of me.

Yes, my experience as well. It feels like people are constantly tailgating me. If we're driving 10-20mph and I can't see your headlights, you're too close!

Have to be really careful as I (and I assume most others) don't feel like we're driving overly slow just to get better mileage, but people can't handle me coasting

to lights 5+ car lengths ahead. Shows you the average driver is an idiot. Hey guess what, if there is a red light ahead of me that I can coast to,

I take my foot off the gas!

 

Needless to say, I get passed alot just because I'm not flooring it downhill all the time.

[alpha754293]

I've had my HyTi for a couple weeks now. This is what I've figured out. I tried "chasing" the EV mode sort of like Corncobs posted above. What I found for my commute is that it tends to run the battery down which effectively gives you decreaing returns because after awhile you have to keep letting off the gas more and more unitl you have to press the gas or the engine just kicks on itself.

 

Now that may be more due to my specific commute so take it for what its worth. I drive 23 miles one way to work. Basically it's a lot stop and go. From a dead stop speed up to 30 then back to zero. I don't do that anymore. if the light ahead is red or just turned red, I just coast on up. But on the stretches where I can drive a bit, I just speed up to where I want to be let off and just keep things constant. I try not to articulate the pedal at all and just keep it steady. What I've found is that I'll suck out of EV mode, but it'll be for a short time then it kicks back in all on it's own. The interesting thing is that battery stays charged a lot more and doesn't end up going all the way dow to say an 1/8 or 1/4 full which really makes for bad efficiency in my experience.

 

Driving this way, I'm still getting the same mileage as I was chasing the EV mode, yet I have a lot more enjoyable driving experience because I can keep up with traffic and I'm not speeding up and slowing down all the time. I can actually just relax and drive.

 

I will say that sometimes the car just does better than other times on the very same commute. I can't explain it. Sometimes I'll pick up .7 or .8 avg mpg on the trip, but then days like this morning... my avg didn't change. I'm certain there are just a lot of subtle things during the drive that affect it.

 

It's always interesting/amusing to see how observant other people are. I usually will cruise unless someone is being a real jerk about it and tailgating me hard. I've had guys that have nearly ran me off the road (they were that bad). I SOOO wished I had the dash cams but a lot of it is kinda useless because the Michigan police are pretty useless at going after stuff like that. They've got bigger problems to worry about. (When between Detroit and Flint, they are both usually within the top 5 on the FBI's most dangerous city list...) so yeah....And the fact that the State is sooo poor and even Detroit's State appointed city budget/fund manager basically threw in the towel and said that Detroit is screwed. So...the combination of all of those things means that there's not much in the way of traffic enforcement. I soooo wished that I was in a cruiser so that I would be able to flip the lights or that I was like a "part time" copper so that I can ram them.

 

*sigh...* I wish I wish I wish.

 

SOME people will eventually figure out that I drive the way I do because it ends up being faster than racing to the light. But others simply just don't get it (which is the vast majority). And then there are those that will do it with me for a while, then race off.

 

 

That exactly how I have changed my driving behavior; let the others race each other to the next light or next slower car; I keep up with traffic but I don't care if there is a gap of several cars between the car ahead and myself.

A lot more relaxing for me but it seems to be more frustrating for others like the one guy behind me this morning in his Roadmaster ready to have a heart attack not being able to chase the car in front of me.

 

Like I said, up here - it's more an optimization method between what's efficient and what's practical/safe. I've read about some of the stuff that hypermilers do and it's like..."*eek*" ...lol...

 

I had someone tailgating me this morning too. I was cruising at 35 (the speed limit) slowing down relatively slow to lights and speeding up gently (EV up to 20 MPH then constant ICE). I couldn't see this guy's hood, only his windshield. He was sooo pissed! It was a one lane road, so he couldn't pass me for like 10 minutes - we were taking the same turns and everything. When we finally got to a 2 lane road he stepped on his gas and raced by me !

 

I just laughed and kept on cruising.

 

Yeah....we have some real jerks up here. I'm pretty sure that there's at least one everywhere, but the worst is when they look at you as if YOU'RE the crazy one. *sigh*...it's too bad that the police here are so lax about the highway patrol. I wished they were more strict/stringent. It'd be a freakin' gold mine and it'd be SUCH easy pickings too...

[corncobs]

Yes, my experience as well. It feels like people are constantly tailgating me. If we're driving 10-20mph and I can't see your headlights, you're too close!

Have to be really careful as I (and I assume most others) don't feel like we're driving overly slow just to get better mileage, but people can't handle me coasting

to lights 5+ car lengths ahead. Shows you the average driver is an idiot. Hey guess what, if there is a red light ahead of me that I can coast to,

I take my foot off the gas!

 

Needless to say, I get passed alot just because I'm not flooring it downhill all the time.

I seriously consider removing the "hybrid" badge on the back to see if that changes the behavior or not; but I guess people would react the same if you would to drive a 500 HP sports car this way; I'm not sure Edited May 20, 2013 by corncobs

[smr2112]

Would not make not difference, nobody pays attention to the Hybrid badge (except us geeks),

most people wouldn't know a hybrid from a Bugatti Veyron.... If you did that in a sports car,

though you might get shot at or at least dirtier looks from those who do recognize it.

[Riggo]

It's funny to me how I used to be one of those people that raced everywhere and now I'm one of the ones that is fine staying in the right lane cruising along while everyone passes me.

I really think a lot of it has to do with how nice the car is and the features of it. It's really relaxing to me to just sit and listen to music in it while I drive along.

[acdii]

I seriously consider removing the "hybrid" badge on the back to see if that changes the behavior or not; but I guess people would react the same if you would to drive a 500 HP sports car this way; I'm not sure

It doesn't, I get the same crap from aggressive Special kind of Stupid drivers when I drive the Flex. Just because I can go 0-60 in 6 seconds, doesn't mean I have to. As all the others said, its the same for me. Can't tell you how many times I have someone ride my butt, then pass me, only to be passed by me at the next light. Then wash, rinse, repeat all over again.

 

Kind of reminds me of smokers, complain about the high cost of smokes, know all the health risks, yet continue to suck on them and put $6 or more a pack up in smoke, money to burn. Imagine all the extra cash you can have if you just slow down and Drive Smarter, not Faster.

[alpha754293]

Yes, my experience as well. It feels like people are constantly tailgating me. If we're driving 10-20mph and I can't see your headlights, you're too close!

Have to be really careful as I (and I assume most others) don't feel like we're driving overly slow just to get better mileage, but people can't handle me coasting

to lights 5+ car lengths ahead. Shows you the average driver is an idiot. Hey guess what, if there is a red light ahead of me that I can coast to,

I take my foot off the gas!

 

Needless to say, I get passed alot just because I'm not flooring it downhill all the time.

 

The problem here is that people have a propensity to tailgate you then rearend you. The WORST is during the summer storm season because as it has been stated several times already, the vast majority of the general driving population are idiots. I see people getting rearended all the time on I-75. I WISHED that if you rear-end someone, you automatically get a ticket (although, I will also say from personal experience, that the one time that I ended up rearending someone else was being it was the day after a snowstorm, and it was sunny and the snow was melting, and this idiot was doing 65 in the far left lane, spun out, lost control, hit the center concrete barrier, bounced off of it into my lane, which resulted in my hitting him.)

 

It's almost like it's better for you to gradually slow down to the point where you piss them off enough that they'll find another way around you. They'll probably flip you off, but it's far better than being hit. THE BEST BUMPER sticker I saw: "If you're going to ride my a$$, at least pull my hair" or something like that. lol....

 

I seriously consider removing the "hybrid" badge on the back to see if that changes the behavior or not; but I guess people would react the same if you would to drive a 500 HP sports car this way; I'm not sure

 

I'm not really sure that people even notice the Hybrid badge to be honest. I think that people generally aren't all that attentive. (cf. Improv Everywhere's "Seeing Eye People" for people who like to walk and text...) ;)

 

Would not make not difference, nobody pays attention to the Hybrid badge (except us geeks),

most people wouldn't know a hybrid from a Bugatti Veyron.... If you did that in a sports car,

though you might get shot at or at least dirtier looks from those who do recognize it.

 

I DO think the car that you drive in as you're doing that DOES make a difference though. If you are driving really slowly in a Corvette, people are probably more apt to think that there's a speedtrap ahead or something. If you're driving a Prius (since that's the car that people most commonly associate with the word "hybrid" or "ecofriendly") they'll just think that you're a psycho tree hugging hipster. lol..

 

That and also if you drive slowly in a Corvette and they pass you, you KNOW that you can mash it and suck the doors off their car as you blow past them again. lol...unfortunately, the same can't be said for the FFH. (NOT that it was designed for it...although the new Porsche hybrid or the new Ferrari hybrid and the new McLaren hybrid would be able to do it).

 

It's funny to me how I used to be one of those people that raced everywhere and now I'm one of the ones that is fine staying in the right lane cruising along while everyone passes me.

I really think a lot of it has to do with how nice the car is and the features of it. It's really relaxing to me to just sit and listen to music in it while I drive along.

 

I think that it might also be an "age" thing (presuming that you were quite young when you used to race everybody). I remember topping out my Cavalier at 104 mph (~170 km/h) before bouncing off the governor. And I also remember that when I was late for work, I would be routinely doing 88 mph (140 km/h) on the backroads of Michigan as I'm rushing to get to work. And then, I started doing only 77 mph (125 km/h) and staying there on the highways. And now I'm perfectly happy/content doing 69 mph (110 km/h) and just cruising along.

 

Some 15 year old chick got busted doing 187 km/h (116 mph) in a 110 km/h (69 mph) zone near Calgary and she didn't even have her license. lol...

 

 

It doesn't, I get the same crap from aggressive Special kind of Stupid drivers when I drive the Flex. Just because I can go 0-60 in 6 seconds, doesn't mean I have to. As all the others said, its the same for me. Can't tell you how many times I have someone ride my butt, then pass me, only to be passed by me at the next light. Then wash, rinse, repeat all over again.

 

Kind of reminds me of smokers, complain about the high cost of smokes, know all the health risks, yet continue to suck on them and put $6 or more a pack up in smoke, money to burn. Imagine all the extra cash you can have if you just slow down and Drive Smarter, not Faster.

 

Yea...people are very hypocritical. And ignorant (which is separate and distinct from stupid). I eventually settled in on 110 km/h because I found that the extra fuel spent to get me there 9% faster just wasn't worth it. And if a trip takes 4 hours, it's going to take 4 hours. That 9% isn't going to make any sort of a dent on anything anyways.

 

But again, it comes back to the whole "people can't do basic math" problem/issue.

[mokee]

The drivers that irritate me are the ones who tailgate in the right hand lane on the Interstate. Some act PO'd like you're in their personal passing lane. My wife calls the right lane "the BMW passing lane."

Edited May 21, 2013 by mokee

[alpha754293]

The drivers that irritate me are the ones who tailgate in the right hand lane on the Interstate. Some act PO'd like in you're their personal passing lane. My wife call the right lane "the BMW passing lane."

 

lollll that's funny. I like that. lol...

[mokee]

I DO think the car that you drive in as you're doing that DOES make a difference though.

 

While towing boats I observed almost all other drivers want to pass regardless of how fast I drrve. I towed a trailer/boat combo weighing 7500# from San Diego to South Carolina. The trailer had a "sprung" torsion axle, so I mostly cruised 55 mph on I-40. The same drivers passed me repeatedly during the trip. Some even stayed at the same motel. We waved at each other.

[kuzzi]

While towing boats I observed almost all other drivers want to pass regardless of how fast I drrve. I towed a trailer/boat combo weighing 7500# from San Diego to South Carolina. The trailer had a "sprung" torsion axle, so I mostly cruised 55 mph on I-40. The same drivers passed me repeatedly during the trip. Some even stayed at the same motel. We waved at each other.

That's a frequent occurrence on my bike. I tend to run it above the "mass average" traffic speed just so I don't have to worry about being in someone's blind spot in the middle of a convoy. Then my little peanut tank only holds 3.3 gallons (2.5g usable due to a tank lift and not wanting to dry the pump out). I pull over, put in my $7.50 of gas every 100 or so miles then get right back up and pass the same group I had passed not 20 minutes before.

 

I think it's odd that I doubled the HP of the bike, but am getting the same fuel economy. I guess the engine just doesn't have to work near as hard as it used to before the conversion and can go along at 4k+ rpm without too much load. Just a constant steady throttle.

[neod192]

While towing boats I observed almost all other drivers want to pass regardless of how fast I drrve. I towed a trailer/boat combo weighing 7500# from San Diego to South Carolina. The trailer had a "sprung" torsion axle, so I mostly cruised 55 mph on I-40. The same drivers passed me repeatedly during the trip. Some even stayed at the same motel. We waved at each other.

I'm one of those drivers :) You never know what gets loose and ends up hitting your car - either something falling out of a trailer or a boat that decides it doesn't want to stay hooked to the car in front of it.

Edited May 21, 2013 by neod192

[alpha754293]

That's a frequent occurrence on my bike. I tend to run it above the "mass average" traffic speed just so I don't have to worry about being in someone's blind spot in the middle of a convoy. Then my little peanut tank only holds 3.3 gallons (2.5g usable due to a tank lift and not wanting to dry the pump out). I pull over, put in my $7.50 of gas every 100 or so miles then get right back up and pass the same group I had passed not 20 minutes before.

 

I think it's odd that I doubled the HP of the bike, but am getting the same fuel economy. I guess the engine just doesn't have to work near as hard as it used to before the conversion and can go along at 4k+ rpm without too much load. Just a constant steady throttle.

 

Yeah...part throttle operation (PTO) is a bit of an oddity.

 

Especially for fixed gear ratio transmissions (which is basically all transmissions that are NOT CVTs). And I say this because in order to hit a certain speed, you need the axle to be spinning at a certain speed. If you have purchased the transmission in your vehicle, then that means that the gear ratio is already predetermined for you (which, unlike an OEM, you can get the gear and transmission manufacturers to GIVE you a gear/transmission with a certain gear ratio so that you can hit your goals/targets). So by that virtue, the speed of your input shaft is also predetermined.

 

That means that the speed of your engine is pre-determined as well. So then the question is would increasing the horsepower (torque) really make that much of a difference?

 

I used to play with this a little bit when I had my old Cavalier and also my old Grand Am to see whether there was any real difference if I was to cruise at highway speeds in 3rd vs. 4th. From a practical driveability standpoint, I honestly couldn't tell the difference. You'd think that with the engine running at a lower engine speed that it would be more efficient, but I think that since it measure the air flow going into the engine and then metering the fuel in that way anyways, that that's why maybe it didn't matter nearly as much. Or that the loss of efficiency (including the multiplicative effects of all of the system inefficiencies combined together) made for only a 1 or 2 mpg difference IF that.

[acdii]

I found that most engines most efficient RPM range is between 1500 and 1700 RPMs, Diesels being up to 1800 RPM. Pans out so far in every geared vehicle I have driven recently. Of course the gearing determines what speed you travel in that RPM range. In the F150 that limited me to 65 MPH, dont know what it is in the Flex yet as I haven't gone over 65 MPH on a cruise and looked at the RPM's. The V8's in the Grand Marquis and Crown Vic were same, right around 1500-1700 got the best economy. This goes back to 1992, the 79 LTD had a C6 and no overdrive, so it ran above 2500 at highway speeds, yet still managed 21 MPG.

[kuzzi]

I found that most engines most efficient RPM range is between 1500 and 1700 RPMs, Diesels being up to 1800 RPM. Pans out so far in every geared vehicle I have driven recently. Of course the gearing determines what speed you travel in that RPM range. In the F150 that limited me to 65 MPH, dont know what it is in the Flex yet as I haven't gone over 65 MPH on a cruise and looked at the RPM's. The V8's in the Grand Marquis and Crown Vic were same, right around 1500-1700 got the best economy. This goes back to 1992, the 79 LTD had a C6 and no overdrive, so it ran above 2500 at highway speeds, yet still managed 21 MPG.

 

That makes me wonder what economy I could get on long trips if my cruising RPM on the bike dropped from 4000 to that 1750 range........ Probably alot less vibration too.

 

In the Bronco II, I plan on replacing the differential to match the diesel's preferred range. It's hard to meet it now with the 2.9L Cologne since the Overdrive was designed when national speed limit was 55mph. It's buzzy at 70 mph.

 

What effect would tire size have on the e-CVT? (assuming we can calibrate the speedo and have the EV modes cut off at the adjusted 62mph)

[acdii]

If your outside diameter stays within reason of the stock tires, should have no affect on the CVT, but YMMV.

 

On the F350 Dually I had with the 7.3Powerstroke Diesel, it came with 4:11 gearing, when I blew out the spider gears horsing around(Never do a burnout in a Dually, no matter how cool it looks), I down sized both front and rear to 3:73 gearing and improved my highway MPG from 18 to 20. It dropped 400 RPM too. at 65-70 it would be spinning at 2100 RPM, after the gearing change it dropped to 1700. On the BII you might want to see if you can find a gearing calculator that uses the tire sizes to determine what final gears to use based on the RPM and output of your trans. I used to be able to do it, but after not doing it for nearly 2 decades, its all fuzzy math now.

[alpha754293]

I found that most engines most efficient RPM range is between 1500 and 1700 RPMs, Diesels being up to 1800 RPM. Pans out so far in every geared vehicle I have driven recently. Of course the gearing determines what speed you travel in that RPM range. In the F150 that limited me to 65 MPH, dont know what it is in the Flex yet as I haven't gone over 65 MPH on a cruise and looked at the RPM's. The V8's in the Grand Marquis and Crown Vic were same, right around 1500-1700 got the best economy. This goes back to 1992, the 79 LTD had a C6 and no overdrive, so it ran above 2500 at highway speeds, yet still managed 21 MPG.

 

I think that on my old '98 Grand Am, doing 77 mph (125 km/h), I would be at around 2500-2750 rpm (I forget exactly). I'd average around 24 mpg.

 

On the 2003 Cavalier, at the same speed, I would be doing close to 3000 rpm, with about the same average fuel economy.

 

it is known that the efficiency (Greek symbol eta) for 3rd gear is less than the efficiency in 4th gear. Therefore; is the change in fuel economy solely because of the change of the engine rpm or is it a combination of the two or is it that the engine efficiency is the same (since the power (and therefore; torque) is the same to hold it at the same speed), but the speed of the engine is higher in a lower gear because of the lower gear, and less efficient because of the known difference between eta_3rd (eta subscript 3rd) and eta_4th?

 

That was actually what prompted the question when I was doing one of my long, boring drives which caused me to play/study it a little bit and to try and think/reason it through.

 

 

That makes me wonder what economy I could get on long trips if my cruising RPM on the bike dropped from 4000 to that 1750 range........ Probably alot less vibration too.

 

In the Bronco II, I plan on replacing the differential to match the diesel's preferred range. It's hard to meet it now with the 2.9L Cologne since the Overdrive was designed when national speed limit was 55mph. It's buzzy at 70 mph.

 

What effect would tire size have on the e-CVT? (assuming we can calibrate the speedo and have the EV modes cut off at the adjusted 62mph)

 

If it's a CVT like it is in the FFH, it should have very little effect because the speed of the engine is somewhat decoupled from the speed of the transmission and the rest of the driveline system.

 

I wished that I had a way to read the transmission control module to figure out how it decides what it is doing. But the general jist of it should be all in the transmission control algorithm that out of the multitude of things that it is constantly monitoring to decide what the transmission should be doing - tire size will likely be "baked into" the wheel speed sensor (in terms of how fast or how slow it thinks it is going vs. how fast the vehicle is ACTUALLY going.)

 

If your outside diameter stays within reason of the stock tires, should have no affect on the CVT, but YMMV.

 

On the F350 Dually I had with the 7.3Powerstroke Diesel, it came with 4:11 gearing, when I blew out the spider gears horsing around(Never do a burnout in a Dually, no matter how cool it looks), I down sized both front and rear to 3:73 gearing and improved my highway MPG from 18 to 20. It dropped 400 RPM too. at 65-70 it would be spinning at 2100 RPM, after the gearing change it dropped to 1700. On the BII you might want to see if you can find a gearing calculator that uses the tire sizes to determine what final gears to use based on the RPM and output of your trans. I used to be able to do it, but after not doing it for nearly 2 decades, its all fuzzy math now.

 

The math itself isn't entirely difficult. We used to use Excel spreadsheet to do this sort of calculation in my chassis/vehicle dynamics and transmission classes using the grossly simplified models for everything. (i.e. we didn't consider the variation of diameter on a tire due to dynamic pressure differences due to different temperatures on the contact patch, etc.)

 

It might take a little bit of time to think through what's going on (the physics of it), but I'm pretty sure that it's fairly readily and easily done. It takes a bit of common sense to figure stuff out, but not "hard" by any stretch of imagination. Keep the model simple initially. We can always throw a whole toolchest of wrenches into the mix to make it ridiculously complicated. ;)