Different method of driving -- my experience getting 50+ mpg

[58Desoto]

I'm a newbie at hybrid driving. But being a retired GE engineer I am always thinking what my drivetran is doing while driving.

My first tank i got 39 mpg with the A/C on. Noticing my battery level drop at red lights i began turning the a/c off at red lights, next tank got 44 mpg.

Turning the a/c off but running the fan seems to keep the compressor engauged as cold air will come out when the fan is running at first start up so i kill everything.

One thing i did notice is the low mpg numbers i was getting in ice mode. After putting some thought into it i began starting from a stop using ice to just below the speed limit then switching to electric and raising my speed to 5 mpg over the speed limit when the ice kicks in i slowly reduce my speed to 5 miles under the speed limit. what this does is to raise my ice mpg as i look at the mpg gauge.

I have yet to use a full tank using this method but every trip i have driven has gotten over 50 mpg with the a/c on and many trips at 56 to 58 mpg when I have the a/c off

Edited September 26, 2016 by 58Desoto

[murphy]

That procedure is known as "Pulse and glide".

 

http://alternativefuels.about.com/od/lifestylecleangreen/a/hyperpulsenglid.htm

[58Desoto]

No. This is not pulse and guild

 

. To initiate a P&G, accelerate to about 40 MPH with the engine running (the pulse part), then ease off the pedal until the engine shuts off and the hybrid system goes into electric mode. At this point, the vehicle's power meter should show zero (or if equipped with an energy flow monitor, no arrows are showing energy flow). This is the glide part. The engine is off, the electric motor is disengaged and the vehicle is literally coasting for free. When the car slows to about 25 or 30 MPH (depending on traffic conditions, of course) repeat the pulse part, then the glide and so on.

 

My method is more of a "pulse and excelerate"

what's different is when i'm running in elec mode I am excellerating slowly but not enough for the ice to start to build up speed that i can burn off when i'm slowing when the ice is running. this raises my ice mpg as it is under a very light load only to recharge the bat and not to keep up speed. that way i can keep up with traffic.

 

i wouldn't try pulse & coasting to 25 in a 50 zone and watch the fingers fly

Edited September 26, 2016 by 58Desoto

[hermans]

This is going to get good.....

[lolder]

Here we go. When you are accelerating, you should do so enough to INSURE that the ICE runs. Do not try to keep it in EV. All the energy comes from gasoline and these hybrids are all about the thermodynamic efficiency of the ICE. The ICE is never run at low throttle plate openings. It is run at almost full throttle and the lowest RPM that will deliver the power called for. It is run at the point just shy of what we used to call "bucking" in too high a gear with too much throttle in manual transmission cars. Acceleration in a non-plug-in hybrid should almost always be done with the ICE on. The low mileage when the ICE is on is caused by the fact that it's power is being used almost equally in propelling the car and charging the HVB. You want to load up the ICE because that's when it operates at the lowest brake specific fuel consumption ( BSFC ). Here is a link to the Prius "fuel map": http://ecomodder.com/wiki/index.php/File:Toyota_2zrfxe_1.8l_prius_bsfc1.jpg. Ford would have similar shapes. The intent is to operate as much as possible within the shaded areas at 220 for the newer Prius and 230 for the older, smaller ICE. There are two engines displayed on this chart. The two solid lines are where the engines actually operate. Here's another link about BSFC: https://en.wikipedia.org/wiki/Brake_specific_fuel_consumption.

Edited September 26, 2016 by lolder

[58Desoto]

"The low mileage when the ICE is on is caused by the fact that it's power is being used almost equally in propelling the car and charging the HVB."

 

Thats my point. By only putting a light load on the ice by allowing my speed to slowly drop aprox 10 mph in 1 to 2 minutes it uses less fuel because of the load the on ice is mostly used in charging the HVB. Though it is propelling the car, by allowing the speed slowdown the ice mpg is increased.

 

ie... Apon moving on ice from a stop my ice mpg shows aprox 10 mpg until i get to speed and the propelling load drops off then it will increase to aprox 20 mpg. Lifting my foot slightly on ice will raise the ice mpg to aprox 30 though my speed will drop. Thats what i am seeing when i slow down to charge the HVB on ice. If i try to keep the speed up my ice mpg will drop to 20. So i'm trading off some speed to save fuel but using the HVB to pick the speed back up. Being able to recharge the HVB through braking at or near 100% I'm sure also helps

 

I always allow the ice to accelerate the car to speed and never try to keep it in EV mode all the time as physics takes over.

 

I have always reset my trip meter on every trip i take. normal local city driving trips of 10 to 20 mile round trips. no hills

Edited September 27, 2016 by 58Desoto

[Waldo]

As lolder says, you either want to run the ICE at its most efficient point or not at all. Its most efficient point is not at light load. Running the ICE only enough to charge the battery does not run it at its most efficient point because the battery cannot accept all the power that the ICE would produce at its most efficient point. That's why when you run the ICE, you want it to both power the car and charging the battery. By slowing down under ICE, you're running the ICE sub-optimally and then you're using battery power to accelerate back up to speed instead of using it to keep a constant speed for longer.

 

The instantaneous MPG is useless in a hybrid. It can't portray the "robbing Peter to pay Paul" nature of the hybrid system. If you run the ICE at 20mpg for 40% of your driving or run it at 10mpg for 20% of your driving, which one burns more fuel?

 

FWIW, I got 60.2MPG on my 20 mile commute home last night! But part of that comes from starting with a fairly full battery and ending with a fairly empty one. On short trips the difference in SOC between the start and end of the trip will influence the MPG number more than any driving techniques you can employ.

Edited September 27, 2016 by Waldo

[58Desoto]

my latest trip 10.6 miles 62.1 mpg all the while keeping up with traffic, no coasting starting out with a low charged HVB which required the ICE to start up and run for the first few miles. my HVB is always low at start as the E+ drains it when i get close to home.

Edited September 28, 2016 by 58Desoto

[58Desoto]

My only goal was to decrease my ice gas usage. i'm just trying different methods of driving. I compleatly understand you cannot create energy from nothing, but without expermenting and keeping an open mind we would all still be driving a model T

[lolder]

The computer systems in hybrids usually do a better job of fuel economy than you can until you have a lot of experience. There are no new tricks. It is my opinion that you should NOT try to keep the ICE from running by encouraging EV mode. Accelerate normally with the ICE, look ahead as far as you can at traffic lights and brake early and slowly to avoid coming to a complete stop. Don't speed. If you are a type A it will be hard to adapt.

[Waldo]

My only goal was to decrease my ice gas usage.

 

That's perfectly reasonable, but as we've explained, what's not obvious is that decreasing the ICE gas usage can often be done by running it harder.

[ptjones]

Just got a new record tank mileage of 915 miles/ 13.8 gal.( 13.7 actual fill up gal.)66.1mpg /644.5 mi. EV , 70.4% EV. Here is what I use to get these numbers. When I start out I EV to 15-20 mph then use ICE at two bar acceleration to 5 mph over speed limit. Then I glide down to speed limit and holding as long as I can in EV to 5 mph under Speed limit. Then start ICE accelerating at two bars again to five mph over SL. and repeat. Sometimes if I get a down hill for a ways I will coast in Neutral instead of Gliding . Gliding is at best 80% efficient as coasting is close to 100% efficient . :)

Paul

[hermans]

my latest trip 10.6 miles 62.1 mpg all the while keeping up with traffic, no coasting starting out with a low charged HVB which required the ICE to start up and run for the first few miles. my HVB is always low at start as the E+ drains it when i get close to home.

You can always turn off EV+

Edited October 3, 2016 by hermans

[md13ffhguy]

When I start out I EV to 15-20 mph then use ICE at two bar acceleration to 5 mph over speed limit. Then I glide down to speed limit and holding as long as I can in EV to 5 mph under Speed limit. Then start ICE accelerating at two bars again to five mph over SL. and repeat.

Glad I don't have to drive behind you! ;)

[ptjones]

Glad I don't have to drive behind you! ;)

Usually this isn't a problem if you have a good HVB SOC I can accelerate pretty good. Interesting comment coming from someone that has a better Fuelly average than I do. :lol: I'm assuming your miles are primarily City, you don't post it on Fuelly. Mine are 82% HWY. All my high mileage tanks have been on trips using State Routes (55-65mph) like this last trip was from Newnan, GA to Savannah, GA to Georgetown, SC to Monticello, GA. :shift: :)

 

Paul

[lolder]

EV+ lowers the HVB charge as you near "Home" because the next time you start the car, probably the next day, the ICE will need to run some additional time to do some evaporative emissions tests and to warm up some ICE components such as the catalytic converter. Charging the HVB up to average during this time will help "load up" the ICE into a more efficient operating power level. Engines are most fuel efficient at moderately higher power settings. They are least efficient at low settings and hybrid cars avoid these areas of operation. Shortly after the 2013 Ford hybrids were introduced with 47/47/47 mpg rating, it became apparent that they couldn't meet these numbers. They did a software update to raise the max EV speed from 60 to the 86 mph of the plug-ins. This was a big mistake as EV is not more efficient than the ICE at these higher speeds. The "Energi's" have an additional transmission cooling pump that the hybrids don't have and it is suspected that might have been the cause of transmission failures in the hybrids.

Edited October 4, 2016 by lolder

[md13ffhguy]

Interesting comment coming from someone that has a better Fuelly average than I do. :lol: I'm assuming your miles are primarily City, you don't post it on Fuelly. Mine are 82% HWY. All my high mileage tanks have been on trips using State Routes (55-65mph) like this last trip was from Newnan, GA to Savannah, GA to Georgetown, SC to Monticello, GA. :shift: :)

 

Paul

Yeah, but I just drive consistently at the speed limit without all the slowing and speeding up. Adaptive cruise control seems to benefit fuel mileage, too.

 

Not sure how anyone can precisely measure city vs highway driving to an exact percentage. I spend a LOT of time on highways, but during rush hour, it's not always at highway speeds.

[ptjones]

Yeah, but I just drive consistently at the speed limit without all the slowing and speeding up. Adaptive cruise control seems to benefit fuel mileage, too.

 

Not sure how anyone can precisely measure city vs highway driving to an exact percentage. I spend a LOT of time on highways, but during rush hour, it's not always at highway speeds.

Interstates HWY's (65-75mph is definitely HWY, also 50 mph above, I think this is HWY and 45 mph and below City. :)

 

Paul

Edited October 9, 2016 by ptjones

[kb9skw]

I bought a used 2015 FFH four weeks ago and have been playing around with it a bit. I drove it on the interstate yesterday at both 65 and 60MPH and got the following results. Mostly Eco Cruse Control all the way.

 

[58Desoto]

Quoting Waldo "Running the ICE only enough to charge the battery does not run it at its most efficient point because the battery cannot accept all the power that the ICE would produce at its most efficient point."

Please explain.

[lolder]

Engine efficiency is measured by a engineering term called Brake Specific Fuel Consumption ( BSFC ) It has nothing to do with car brakes. BSFC is weight of fuel per power output. The lowest and most efficient BSFC is achieved at ICE power levels above that demanded by solely charging the HVB. There is a limit on how much power HVBs can accept while charging. Hybrid ICE's never "Idle". They never operate below about 1000 rpm and then the throttle plate in the intake air manifold is almost wide open as compared to just barely cracked in a conventional ICE. Hybrid ICE's are only run at a point just shy of what used to be called "bucking" in a straight stick manual transmission car where you pressed too much on the accelerator pedal in too high a gear. That is the most efficient operating point but even that point is less efficient than ones available at higher power. In a non-plug in hybrid, it's all about operating the ICE at the best thermodynamic ( heat ) efficiency.

Here is a link to a Prius "Fuel Map": http://ecomodder.com/wiki/index.php/File:Toyota_2zrfxe_1.8l_prius_bsfc1.jpg.

Fords have a similar shape. The picture is confusing because there are two Prius ICEs described, the 2001-2003 1.5 liter 1NZ-FXE and the 2004-2016 1.8 liter 2ZR-FXE. The bold lines are where the computer tries to operate the ICE. The most efficient areas are within the darker shaded regions of 230 g/kWh for the 1.5 liter and 220 g/kWh for the 1.8 liter. The bigger ICE has a lower BSFC than the smaller one and that translates to the fact that the larger, newer Prii get better mpg. These areas are considerably up and to the right from the intersection of the vertical and horizontal axis which is in the direction of higher power.

This is technical stuff but that's what it is.

Edited October 15, 2016 by lolder

[ptjones]

I did this for the CMAX Energi Forum to explain how to get the MAX FE:

 

First: Grill Covers improve aerodynamics by 1.5-2 mpg using ICE and should do the same in HVB EV Mode. I almost never take my Grill Covers off and when I do it's just the lower one.

Second: You would think because all the energy comes from the ICE that if you run it all time you would get your best FE, right? Wrong! FE problem turns out to be more complex than that. I have tried running My Hybrid ICE all the time which by the way is very hard to do. What I did was filled up and got on I-40 going home and after about fifty miles FE seemed to stop going up so I went back to my normal Pulsing uphills and EV down and almost immediately my FE went up and kept going up.

Third: To get best FE the ICE needs to be at Operating Temp according to FORD (202-212*F) and This happens rarely without Grill Covers. With Grill Covers on from a cold start it takes me at least 20 minutes on the FWY when it's warm out to get to 202*F.

Forth: You need to be at the maximal efficiency for the ICE which I believe is at Two Bars on Empower Display, I have noticed when accelerating the ICE power bar will stop at two bars and requires additional pressure to go pass that point and it seems to charge the HVB the fastest there too.

This would apply to CMAX Hybrid/FFH and NRG's in Hybrid Mode:

This from Wikipedia: https://en.wikipedia...ting_or_gliding

______________________________________________________________________________________________________________________________

Causes of pulse-and-glide energy saving

Much of the time, automobile engines operate at only a fraction of their maximal efficiency,^[24] resulting in lower fuel efficiency (or what is the same thing, higher specific fuel consumption (SFC)).^[25] Charts that show the SFC for every feasible combination of torque (or Brake Mean Effective Pressure) and RPM are called Brake specific fuel consumption maps. Using such a map, one can find the efficiency of the engine at various combinations of rpm, torque, etc.^[23]

During the pulse (acceleration) phase of pulse and glide, the efficiency is near maximal due to the high torque and much of this energy is stored as kinetic energy of the moving vehicle. This efficiently-obtained kinetic energy is then used in the glide phase to overcome rolling resistance and aerodynamic drag. In other words, going between periods of very efficient acceleration and gliding gives an overall efficiency that is usually significantly higher than just cruising at a constant speed. Computer calculations have predicted that in rare cases (at low speeds where the torque required for cruising at steady speed is low) it's possible to double (or even triple) fuel economy.^[22] More realistic simulations that account for other traffic suggest improvements of 20% are more likely.^[23]

These two- or three-fold improvements in fuel economy are possible only at city driving speeds of say 25 or 35 miles/hour. This is because cruising (steady speed) at such low speeds is very inefficient since the torque needed is so low that the efficiency read on a BSFC map is very poor. Pulse and glide significantly improves this. Unfortunately, city driving often involves many stops at signals and stop signs which were absent in the computer simulation^[22] which showed such multiple fold improvements. In other words, in the real world one is unlikely to see fuel efficiency double or triple. Such a failure is due to signals, stop signs, and considerations for other traffic; all of these factors interfering with the pulse and glide technique. But improvements in fuel economy of 20% or so are still feasible.^[22][23][26]

^{This goes along with "louder Post #21 and covers most of the things that can be done to improve FE plus 50psi tire pressure. :shift:} :)

Paul

[md13ffhguy]

So there you go, two posts - science and non-science (or nonsense?). Grill covers are not necessary, and neither is pulsing and gliding (aka erratic driving).

[ptjones]

So there you go, two posts - science and non-science (or nonsense?). Grill covers are not necessary, and neither is pulsing and gliding (aka erratic driving).

 

 

This thread is about improving MPG's, you don't have to do it, but others might be interested and this is all based on actual testing.( Science) :) I have 5 tanks better than 61 mpg, with two at 68mpg. :yahoo: :shift: So this Science actually works, it's unfortunate that some members will put down MPG Tips proved with testing which they haven't tried it themselves. ;( It is interesting that not one member on FFH/CMAX Forums that have tried Grill Covers on their cars say they don't work. :)

 

[md13ffhguy]

I have tried grill blocking (the first winter) with marginal benefit, mostly in warming the car a little quicker. I did a good, neat job, but didn't think the effort was worth my time the next two years. I get really good results by following one simple technique - driving gently. I drive the speed limit, stay to the right, and brake and accelerate gently (not so gently that it annoys anyone behind me).