How Ford achieved 47 MPG in testing, and why you can't in the real world

[hybridbear]

After driving our 2013 Ford Fusion Hybrid to CA and back from MN I have a theory about how Ford achieved 47 MPG in testing when many of our results seem to belie that claim. This theory also explains why Ford is offering to work with the EPA to establish new testing standards for hybrid vehicles.

 

First off let me say that I have no affiliation with Ford or the automotive industry. I'm also not a journalist, I'm a Business Analyst and a math nerd. Because I have a form of autism called Aspergers I pay lots of attention to numbers and data and pick up on patterns in data subconsciously. My thoughts here are only a theory of how Ford could possibly have achieved 47 MPG in their EPA testing when many car owners are not reaching that number. Please let me know if you have any other theories or ideas.

 

First off, we need to understand how the EPA testing procedures work and the rules governing those tests. There are a number of different testing cycles used by the EPA. These cycles are designed to simulate “typical” driving patterns. Details of the cycles, including graphs, can be found at http://www.epa.gov/nvfel/methods/quickdds.htm. An explanation of the distinct cycles can also be found at http://www.cleanmpg.com/forums/showthread.php?t=1510.

 

What are the limitations of the EPA cycles? Let’s first examine the city cycle. The city cycle involves a lot of acceleration and braking. However, there is not much time spent idling as if at a red light. During this test the Fusion Hybrid could spend a lot of time in EV mode, possibly even often accelerating in EV mode depending on the SOC (state of charge) of the battery. The EPA test procedures call for very slow acceleration, unrealistically slow in fact. The maximum acceleration rate in the EPA testing is 3.3 MPH/second. At that rate it would take about 18 seconds for 0-60 MPH. That is not the constant acceleration rate, that is the maximum acceleration rate. At other parts of the testing the acceleration is even more languid.

 

The highway cycle also has its flaws. The highway cycle calls for a maximum acceleration rate of 3.2 MPH/second, even slower than in the city cycle. The highway test also does not measure fuel economy at a constant cruising speed. The graph looks more like what your speed would look like if you were doing pulse & glide for maximum fuel economy. The average speed is 48 MPH and the maximum speed is 60 MPH. This cycle includes no stops, no idling and begins with the engine already warm. All those factors will contribute to higher highway fuel economy.

 

To help offset these disadvantages the EPA created the high speed cycle in 2008. The high speed cycle includes faster acceleration and a top speed of 80 MPH. However, the average speed in the high speed cycle is only 48 MPH. If you look at the graph you can see that it includes multiple stops and time spent idling. The high speeds are sustained only for a very short period of time. This test also starts with a warm engine.

 

Then there’s the AC cycle with warmer temperatures. This cycle is designed to lower the overall fuel economy numbers to be more realistic with summer driving using the AC. The cold temperature cycle is a repeat of the city cycle except with the lab temperature lowered to 20 degrees. This test also includes a cold engine at the start.

 

What are the overall limitations with the EPA tests? The highway speeds are too low for starters. We now have roads with speed limits as high as 85 MPH and many highways, even in the city, are increasing their speed limits up to 65 MPH. The EPA highway cycle looks more like typical driving on suburban county roads for someone who lives out in the outer-ring suburbs. The tests also underestimate the amount of time spent idling in city driving. Most city commutes are going to have a lot more time spent idling than the tests show. The tests do not include the use of AC or heat. In many parts of the country AC is a necessity for most of the year, and heat for the remaining months. The tests also don’t account for winter driving conditions. Lowering the temperature in the lab to 20 degrees is not the same as driving in winter. There is more resistance in the winter due to snow, sand and salt on the roads. But, the biggest flaw though is the cycle length. In an 11 mile city drive the fuel economy will be markedly better than in a 5 mile city drive. An 11 mile city drive is much too long. Most of our trips in the city are less than 2 miles, with the occasional trip being between 5 & 10, but very rarely do we do a city drive more than 10 miles. This greatly affects fuel economy in the Fusion Hybrid because of waiting for the engine to warm up. The EPA does not state that the heat should be turned on for the cold temperature cycle. In a hybrid this is very important, as turning the heat on will keep the engine running thus lowering MPG results. Driving with the heat off in cold weather will raise the MPG numbers, but is not realistic. The EPA test cycles factor in the aerodynamics of the vehicle but not wind. Wind is a big factor in highway fuel economy. In some non-scientific tests that I have done with our Fusion Hybrid I have found that a 10 MPH crosswind can lower fuel economy by 2 MPG or more.

 

So, now that we understand the limitations of the EPA cycles we can focus on Ford. I fully believe that Ford also identified these limitations and built the Fusion & C-Max to take advantage of the unreal reality that is the EPA tests. For example, why program the Fusion and C-Max to do a maximum of 62 MPH in EV mode? Where does that number come from? Why 62 MPH and not 60? Or 65? Or 55? The answer can be found in looking at the EPA test cycle graphs. The city cycle includes a maximum speed of 56 MPH, in the highway cycle the max speed is 60 MPH, 54.8 MPH in the AC cycle and 56 MPH again in the cold temperature cycle. This means that in all those tests the Ford hybrids can potentially run in EV mode the entire cycle. And while we know that the car could not go the entire distance under battery power, we do know that as soon as the cycle calls for deceleration the Ford hybrids can switch over to EV mode for gas free coasting.

 

Ah, but what about the high-speed cycle you say. Take a look at that graph too. Even though it calls for a maximum speed of 80 MPH, the time spent above 62 MPH is minimal. The test calls for cruising around 62 MPH and then acceleration up to 80 MPH for less than 60 seconds. Once that one minute burst of speed is over the cycle calls for speeds that are mostly below 62 MPH. I believe that Ford specifically identified the 62 MPH EV mode limit as the best way to maximize their results on the EPA cycles, not necessarily as the best way to maximize fuel economy for their customers.

 

In what other ways could Ford have manipulated the results? What about the battery SOC at the start of each cycle. The EPA doesn’t have strict guidelines for hybrids like there are for gasoline cars. While the EPA does specify for each cycle whether it starts with a cold engine or a warm engine, nothing specifies the hybrid battery SOC. From more unscientific testing that I have done, starting with a near 100% SOC is worth easily 5 MPG over starting with the SOC under 25% in short or medium length trips, like the EPA test cycles. This effect is magnified in highway driving because at higher speeds the engine spends a larger percentage of the distance running than in city driving. By watching the instant fuel economy gauge on the dash it is possible to see this effect while cruising on the highway. For example, cruising on flat ground at 60 MPH the instant fuel economy will show somewhere between 35-45 MPG depending on the ambient temperature if the battery is nearly full. When the battery SOC is low, the same conditions yield an instant fuel economy of 20-30 MPG. That’s a big difference, 15 MPG. So if Ford starts the highway cycle with the battery SOC near 100%, then the car will be able to spend more time cruising in EV mode and less time returning 20-30 MPG while recharging the battery.

 

My second theory is thus that Ford started the different test cycles with a battery with a SOC well higher than 50%. And, since the EPA has not established guidelines regarding the SOC of hybrid batteries for the test cycles Ford did not break any rules in doing this. Thus, Ford now offers to work with the EPA to develop new testing procedures for hybrids that would account for such measures. That offer is a smart move on Ford’s part because they can then say that they are working to satisfy consumers by “building a better mousetrap” as it were.

 

What can we do about it? In short, nothing. I don’t think the lawsuits will succeed, and unless the EPA finds that Ford broke some rule we aren’t going to see a refund like Kia & Hyundai were forced to hand out. There is a reason why the EPA mileage estimates come with the disclaimer: “Your mileage will vary”. This disclaimer is there because the tests have their flaws and limitations. What do we do then? Rather than complaining and trying to sue Ford, people need to grow up and learn to deal with it. Before we bought our Fusion Hybrid we test drove the Fusion & the Camry Hybrid. The Camry is rated much lower by the EPA for fuel economy (40/38/40). I wanted to see for myself. So my wife and I drove a specific route that simulated our normal driving. Our testing revealed 46 MPG overall in the Fusion and 45 MPG overall in the Camry doing the same driving route. “Your mileage will vary.” Does this mean that Toyota understated the fuel economy of the 2012 Camry Hybrid? No, it simply means that “your mileage will vary”.

 

The EPA fuel economy numbers are estimates. What is an estimate? It is a rough calculation or an approximation of a value. The EPA estimates that you will get 47 MPG. That means that if you drove the EPA test cycle 100 times you should come out with 47 MPG as the average. Some times you might get 50 MPG, other times 45 MPG, etc. This does not mean that you will get exactly 47 MPG driving to work, to the store, to the mall, etc. This means that if you follow the very specific guidelines the EPA sets forth, and drive in a lab, with no AC, with no wind, with no cargo weight in the car you will get 47 MPG. However, if you are not driving in a lab, with no AC, with no wind, with no cargo weight in the car and are driving to work, school or the mall, then “your mileage will vary”.

 

Really what is needed to find the solution to this conflict is not a lawsuit against Ford. Ford never states “you will get 47 MPG”, they merely hype the fact that the EPA test cycles return 47 MPG. And, what’s wrong with them doing that? It’s their right to advertise the EPA estimates of their cars. And it’s our responsibility as consumers to make wise decisions based, not on advertising alone, but on other factors.

 

So what if the EPA mileage is 47 MPG and you’re only getting 38 MPG? Have you considered all the factors that make your driving different from the EPA test cycles? Do you ever drive on windy days? Are you driving in warm weather with the AC turned on? Are you accelerating faster than 3.3 MPH/second? Are you driving faster than 60 MPH? If the answer to any of those questions is “yes” then you have your answer as to why you aren’t getting 47 MPG. Since none of us drive the EPA test cycle on a daily basis, is it any wonder then that we don’t see 47 MPG?

 

Maybe what’s needed here is a change in perception, a change in how we think about the EPA estimates; not of a lawsuit and a bunch of whining.

Edited January 28, 2013 by hybridbear

[Ric]

"WOW", thanks for the imput. You sure sound like you know what your talking about. What about premium gasoline? Do you think that would make a difference?

[lolder]

"WOW", thanks for the imput. You sure sound like you know what your talking about. What about premium gasoline? Do you think that would make a difference?

No, premium gasoline has no more energy per gallon.

[B25Nut]

"Maybe what’s needed here is a change in perception, a change in how we think about the EPA estimates; not of a lawsuit and a bunch of whining."

 

Agree completely. The word "lawsuit" turns my stomach.

[GrySql]

Well done, I concur with your observations.

It has been my feeling from early in owning this car that, if Lab conditions were met and the car performing in a nominal fashion, the mileage would be the same as advertised.

I posted that opinion and agree with your 'theory' on Ford optimizing these vehicles for test results.

Edited January 27, 2013 by GrySql

[ptjones]

"WOW", thanks for the imput. You sure sound like you know what your talking about. What about premium gasoline? Do you think that would make a difference?

 

No, premium gasoline has no more energy per gallon.

From mine and many others experiences Premium and No Ethanol regular will increase your mpg's by 1-2mpg. EPA uses No Ethanol regular for their testing.

47MPG city is easy, I'm currently doing better than that wiith temps in 40-50deg.F. using my Grill Covers and when temps reach 70-75deg.F I will be pushing 60MPG.

47MPG Hwy is a little harder depending how you define HWY. At 60mph ,70deg.F and Grill Covers on you should be able to do it easilly, I'm doing it now at 50degl.F.

At 70mph at 70deg.F you are looking at 40mpg add 2 for Grill Covers and 2-3 for drafting you are still short by 1-2mpg. Maybe at 80deg.F you could do it but then AC becomes a problem. It would take a tail wind to make it happen.

These numbers will very with driving stile and I'm not sure if all cars are built equal.

[lolder]

No ethanol regular has about 4 % more energy per gallon. Premium does not have more energy per gallon and is a waste in cars. Even those specifying it only gain a few top end HP. when using it and will run fine on regular. Premium allows higher BMEP, not lower BSFC.

[acdii]

The only way I can get to even 40 MPG is to accelerate very slowly, 0-55 in about 30-45 seconds. The 13 is much more difficult to achieve decent MPG than the 10 is.

 

As far as premium goes, it all depends on the engine. When I had the F150, running on 87 octanes would get 16 MPG, but running on Premium would see 18 MPG. The Ecoboost ran a lot more efficient on premium. At Interstate speeds though, didnt really make much difference whether it was 85 or 92 octane. It seems only city/highway mattered.

[acdii]

Ford should have taken lessons from Toyota on marketing. It's one thing to ace the EPA tests, its another to market the car with more realistically obtained numbers. Both the Prius and Camry hybrids I had, met and exceeded their EPA numbers, in fact the 2007 Prius I had was rated old school 60 city 50 highway, and while I never really drove it in city traffic, I did do very well on the highway, the lifetime on it was 53. The Camry exceeded the 34 EPA by 4 MPG. The 2010 FFH is spot on, and I have also exceeded the 36 highway by huge numbers in it.

 

One odd thing I noticed about the 2010, if we short fill it, add gas when there is more than a half tank, the MPG is quite low, and far off from what we were actually getting, but if we fill when its under 1/4 tank, then the calculations are withing a MPG of the dash.

 

This will bite Ford though, if the majority of owners cant achieve these numbers in either car, there will be backlash against them and people will not buy them. If it turns out Ford did fudge the numbers like Hyundai. even worse.

[pers69]

Thanks for taking the time to write that all out, hybridbear. Nice post,

[acdii]

30.8 mile trip, average speed 40MPH. Max RPM 2247. Max speed 63MPH(downhill). Anyone want to take a guess at MPG? Temps in mid 40's too, much warmer than the past 2 weeks by at least 40 degrees.

[neod192]

30.8 mile trip, average speed 40MPH. Max RPM 2247. Max speed 63MPH(downhill). Anyone want to take a guess at MPG? Temps in mid 40's too, much warmer than the past 2 weeks by at least 40 degrees.

37 MPG?

[coach81]

Nice thread... thanks for all this info.

[Fynack]

Nice write up ... Ford may have aced the EPA test but their being dishonest in advertising when no one can reasonably ever reach that magic 47/47/47 number. It may not be illegal but its definitely dishonest and unethical. I buy cars every 2 years and have yet to have a car that didnt meet or stay around their ""EPA Estimated Numbers"". Even with all the details you stated, having AC on, heat on, cold start, accelerating faster then 3.3mph, driving faster then the speed limit , i can meet EPA estimates on my past 10+ cars that ive owned. You may call it whining but i paid a price based on those numbers and my expectations were supposed by the sales person. So should I be at fault??

[ptjones]

30.8 mile trip, average speed 40MPH. Max RPM 2247. Max speed 63MPH(downhill). Anyone want to take a guess at MPG? Temps in mid 40's too, much warmer than the past 2 weeks by at least 40 degrees.

Looking for smoking gun. Do you have much exhaust soot like ICE is running rich? My CMAX has some.

[hybridbear]

Thanks for all the feedback.

 

Ford should have taken lessons from Toyota on marketing. It's one thing to ace the EPA tests, its another to market the car with more realistically obtained numbers. Both the Prius and Camry hybrids I had, met and exceeded their EPA numbers, in fact the 2007 Prius I had was rated old school 60 city 50 highway, and while I never really drove it in city traffic, I did do very well on the highway, the lifetime on it was 53. The Camry exceeded the 34 EPA by 4 MPG. The 2010 FFH is spot on, and I have also exceeded the 36 highway by huge numbers in it.

 

One odd thing I noticed about the 2010, if we short fill it, add gas when there is more than a half tank, the MPG is quite low, and far off from what we were actually getting, but if we fill when its under 1/4 tank, then the calculations are withing a MPG of the dash.

 

This will bite Ford though, if the majority of owners cant achieve these numbers in either car, there will be backlash against them and people will not buy them. If it turns out Ford did fudge the numbers like Hyundai. even worse.

 

I agree that many other cars exceed their EPA numbers. Before purchasing our FFH we had a 2006 Honda Accord Hybrid. The HAH was rated at 22/31/25. The old EPA calculations had the HAH at 25/34/28. We usually averaged over 30 combined with city MPG in the high 20s and highway MPG above 40 in the summertime. Before the Honda I had a 2002 Saab 9-3. That car is rated 18/27/21 under the new EPA guidelines and 21/29/24 under the old EPA tests. In my Saab I usually got above 25 MPG combined with highway driving being above 32 MPG. Both those cars exceeded their EPA ratings, as did the Camry Hybrid we test drove like I mentioned above. It is disappointing that the FFH doesn't beat the EPA numbers like most other cars. And I fully agree that this will hurt Ford in the long run. If people keep clamoring about the poor mileage then consumers are going to shy away from these vehicles.

 

However, what's Ford to do in that scenario? They can't understate the EPA mileage on the stickers just because the EPA tests are flawed. That's why Ford has come out and basically said that the EPA tests need to be changed for Hybrids, because they know they built a car to excel at the EPA tests and to take advantage of their flaws.

 

Nice write up ... Ford may have aced the EPA test but their being dishonest in advertising when no one can reasonably ever reach that magic 47/47/47 number. It may not be illegal but its definitely dishonest and unethical. I buy cars every 2 years and have yet to have a car that didnt meet or stay around their ""EPA Estimated Numbers"". Even with all the details you stated, having AC on, heat on, cold start, accelerating faster then 3.3mph, driving faster then the speed limit , i can meet EPA estimates on my past 10+ cars that ive owned. You may call it whining but i paid a price based on those numbers and my expectations were supposed by the sales person. So should I be at fault??

 

Is it really dishonest and unethical though? Ford never says that you'll see 47 MPG, they say that the EPA test results equal 47 MPG. We can see greater than 47 MPG in the city in warm weather, we even saw 47 MPG on the highway in the warm weather. I guess this is a case of buyer beware...that's why we extensively tested the fuel economy for ourselves...not just trusting what the EPA rating is. In past cars I have also easily done better than the EPA estimates and I figured I would do the same in this car. In past cars I've even beaten the EPA estimates in winter driving which is not easy to do in Minnesota. It's now clear that with the Fusion we won't beat the EPA estimates in the winter, we should in the summer though.

 

In the end I think this all comes down to the word "estimate". Nothing is guaranteed, except death & taxes as the expression goes. So we just have to live with it and learn the lesson for next time. Some people have commented that Ford should offer to buy the cars back from dissatisfied customers. I can't see it getting that bad, but maybe Ford will offer to do that to help assuage the concerns and outrage that people are expressing right now. We can only wait & see. I'm sure these issues are getting a lot of attention at Ford Corporate.

[acdii]

OK, here is proof the 2010 Fusion can excel in surpassing EPA rating of 39 combined. This is combined city/highway from today, 40* temps, and falling

 

[acdii]

Looking for smoking gun. Do you have much exhaust soot like ICE is running rich? My CMAX has some.

Oh yeah, the tailpipe is black with soot. I forgot about that.

 

37 MPG?

Close, 36.5

 

Trip home tonight I really made the effort, and got it to 39.1. I can just imagine what it can do when running right

[Fastronaut]

This is like eating sausage and then seeing how it's made. VALUABLE posts, all. Thanks.

[kuzzi]

I wonder if during testing, the car saw the EPA facility as "Home" and was in EV+ mode?

[Fynack]

I wonder if during testing, the car saw the EPA facility as "Home" and was in EV+ mode?

Most likely it did, considering there is no specific EPA facility they have to test at. They just have to test and then post results. Still waiting for the EPA test .... hopefully the results come soon.

[expresspotato]

Yeah I was wondering the same thing... What ever happened to that EPA investigation?

[Barsoom]

Having once toured a gasoline company test facility, I wonder if the EPA testing was done on a treadmill rather than on an actual road?

 

If it was on a treadmill, then there isn't the effect of wind resistance on the car, which would cause a car to need more power than a treadmill test requires.

 

The gasoline company puts the car on rollers and lets the car run for hours and hours in a stationary position while hooked up to monitoring equipment. It's true that the gasoline company is testing for engine deposit build-up and not necessarily mpg, but do we know what the EPA test requires? Is it actual road driving or treadmill driving?

[corncobs]

Treadmill!

The effect of wind resistance is calculated into the result. The same thing happens with AC usage it's not actually tested / measured its just calculated according to EPA guidelines.

 

I read this somewhere might even been on this forum!

[djminfll]

http://www.fueleconomy.gov/feg/how_tested.shtml

 

 

Skip to main content

Mobile | Español |Site Map | Links | FAQ | Videos | Contacts

• Find a Car
• Save Money & Fuel
• Benefits
• My MPG
• Advanced Vehicles & Fuels
• About EPA Ratings
• More...

Share on facebookShare on twitterShare on emailShare on print|More Sharing ServicesShare

How Vehicles Are Tested

Fuel economy is measured under controlled conditions in a laboratory using a standardized test procedure specified by federal law. Manufacturers test their own vehicles—usually pre-production prototypes—and report the results to EPA. EPA reviews the results and confirms about 10-15 percent of them through their own tests at the National Vehicles and Fuel Emissions Laboratory.

• Go to page 1
• Go to page 2
• Go to page 3
• Go to page 4

Previous PageNext Page

Estimating MPG with Laboratory Tests

1. 

   In the laboratory, the vehicle's drive wheels are placed on a machine called a dynamometer that simulates the driving environment—much like an exercise bike simulates cycling.

   The energy required to move the rollers can be adjusted to account for wind resistance and the vehicle's weight.
2. 

   On the dynamometer, a professional driver runs the vehicle through a standardized driving routine, orschedule, which simulates “typical” trips in the city or on the highway.

   See video

3. 

   Each schedule specifies the speed the vehicle must travel during each second in the test.

   Right: The driver watches a computerized display that shows his driving statistics compared to the specified schedule.

   See video
4. Measuring Fuel Use

   For vehicles using carbon-based fuels (e.g., gasoline, diesel, natural gas, etc.), a hose is connected to the tailpipe to collect the engine exhaust during the tests.

   The carbon in the exhaust is measured to calculate the amount of fuel burned during the test. This is more accurate than using a fuel gauge.

   This method does not work for vehicles using non-carbon-based fuels, such as fuel cell vehicles and electric vehicles.

• About the Ratings
• Your Mileage Will Still Vary
• Fuel Economy Tests
  • Which Vehicles Are Tested
  • Detailed Test Information

Mobile | Download EPA's MPG Ratings | Find and Compare Cars | USA.gov | Info for Auto Dealers | Privacy/Security | Feedback

This site last modified Friday July 26 2013