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Differences Between Automakers’ US MY 2007 New Fleet Fuel Economy Decreases with Increasing Weight of Vehicle

Combined laboratory fuel economy values for all new light-duty vehicles by marketing group from 1975-2007. Click to enlarge.

The 32 years since the implementation of CAFE regulations have seen a convergence in average new fleet fuel economy for light-duty vehicles from the different major marketing groups, according to data published by the EPA in its report Light-Duty Automotive Technology and Fuel Economy Trends: 1975 Through 2007.

Data is for the unconverted laboratory test cycle results—therefore the change in the adjustment methodology made for MY 2008 estimates does not affect the results.

Although GM, Ford and Chrysler improved their total fleet averages over the past 32 years, those averages still are the lowest of the major groups. However Honda, which had the highest average of any group in 1977 with an total average of 35.5 mpg in 1977, has seen that average drop down to a projected 28.7 mpg in 2007 as it diversified its product line. According to the EPA, Toyota will just slightly edge out Honda for the top total new fleet fuel economy average in 2007, with 29 mpg.

Comparing GM and Toyota average new vehicle fuel economy in the 2,750-3,000 pound and 6,000-6,500 pound weight bands.

However, when viewed from the different weight-based categories, the differences between companies such as GM and Toyota are not as stark. GM and Toyota turned in relatively equivalent average new car fuel economy results for vehicles in, for example, the 2,750-3,000 pound weight band—until Toyota introduced the Prius and it began having its sales successes. (See chart at right.)

For heavier vehicles between 6,000-6,500 pounds, however, GM comes out on top in 2007 with an expected 20.1 mpg average—the best of any of the automakers.

Average new fleet fuel economy in mpg by weight category for each of the major automaking groups. Click to enlarge.

The unadjusted laboratory results for model year 2007 for the major automakers by weight category show increasing convergence in average fuel economy with the increasing size of the vehicle. (See chart at right.)




Considering the interior space of the Corolla, the weight of the car is very reasonable; 1150 kg (2535 lbs)
this, and the small 1.8 liter engine contribute to the good fuel economy of this car.
The Yaris sedan weights 1050 kg (2315 lbs) but the interior space is not as good as in the Corolla.


Normalizing by weight tends to hide the main problem - why does it take a 6000 pound vehicle to move a 200lb person to work and the supermarket - when a 2300lb vehicle could do the job.

- or (in some cases) a 25lb bicycle, or a 0.5lb shoe - (which might yield a 160 lb person).

We discussed this earlier - should mpg be grouped by weight - or interior volume (or ground shadow) or not at all.

All to play for.

Harvey D

Dring the last 30+ years of innovative, creative and breath taking engineering and updated CAFE, the world 20 some car manufacturers have managed to reduce how far we drive with one gallon of gas by an average of about 33%. They are not doing better lately.

At that rate, one can wonder where we will be at in another 30 years.

Finding reasons not to improve mpg will not be too difficult, i.e. bigger, faster units; larger brakes and engines; more on board energy consumming gadgets, etc.

Since CAFE and voluntary commitments have not worked, would a progressive $100+/tonne carbon tax applied over 10 years be a better approach?


My '05 Corolla has decent trunk space, interior space in the back for hauling friends, and in the two years I've owned it, has rarely gotten less than 32mpg. I don't really miss my RAV4, though I do sometimes wish I'd gotten a Mazda3i with a stick shift. Sporty, fun to drive, and fuel efficient at the same time.

What bothers me more than anything are the full-sized trucks and SUVs with a 12-18" lift and massive chrome wheels, tires that probably cost $300 each, and growling V8s that probably get worse mileage than a big rig semi.

James White

Gas prices go up and mileage goes down. It's amazing how marketing can triumph over economic reason and intellect.

Roger Pham

One solution for improving the fuel efficiency of large personal vehicles: Restrict maximum acceleration performance of all personal vehicles, in proportion to the weight of the vehicle. For example, a 2500-lb vehicle is allowed 0-60 mph time of not under 9 seconds, a 3000-lb vehicle is allowed 10.5 seconds...and a 6,000 lb vehicle is allowed 16-18 seconds...etc.

On the surface, it may appear cumbersome for the auto mfg's to have to remember all the numbers, but, in reality, if properly instigated, it allows the auto mfg's to build ONE ENGINE that will satisfy ALL MODELS, regardless of size or weight! For example, a 2,500 lb Corolla with its 4-cyl. 120-hp engine is pretty zippy, at 9 seconds, but put that 120-hp 1.8 liter engine into a Camry and performance would still be fast at 10.5 seconds, put the same 4-cyl 120-hp engine in an Avalon of 3500-4000 lbs and 0-60 at ~12 seconds would still be very adequate...and putting the same engine in a 5,000-lb SUV (Highlander) (eh...make it an UV, or Utility Vehicle, scratch out the Sport) will give time of about 15-16 seconds...not very exciting but hey, what do you want in an Utility Vehicle with a main purpose of hauling commercial stuffs and off-road capacity? Remember that at 120 hp, a 5,000-6,000 SUV's still is 3x overpowered in comparison to a 80,000-lb tractor-trailer rig having a 450 hp engine.

This will greatly reduce the sale potential of over-weight SUV's, restricting them to those with legitimate needs to have such a vehicle instead of for vanity reasons...and this will greatly improve the mpg's of such heavier personal vehicles! (without any expensive gimmicks such as hybrids, diesel, 2-mode hybrid, cylinder de-activation...etc.)


Roger, what about towing capacity? How is a 120hp Highlander supposed to pull even a small boat? Or a travel trailer? Don't forget that semi-truck is using a very torquey diesel engine, not gasoline. And the engines themselves are huge. You don't see a 1.8L diesel in a semi. Freightliner lists displacements of 12.8-15.2L for its Cascadia line.

Look, as much as I hate those lifted pickups, I'm not willing to ban them for efficiency reasons. Safety reasons, maybe.

Acceleration is not the problem. It's the overall efficiency of the system under various duty cycles. Acceleration doesn't matter that much to a semi-truck because they spend the vast majority of their time at highway speeds.



John Schreiber

@ Cervus,
I agree with Roger, Though I would bump up the HP limit to say 160. What about towing capacity? Mostly it is about braking. If you need to pull a travel trailer over the mountains, you get a turbo, gas or diesel. (or a smaller travel trailer, or a tent).
The performance Roger speaks of is basically what we saw in the late 70's and early 80's. V8 Fords made no more than 140HP. In fact, a Ford Fiesta was as fun to drive as a V8 Mustang, if both were stock.
It is all about overconsumption, and for what? ego?


To Roger regarding vehicle acceleration:

Maybe in Vietnam or Cuba they maight accept such poor acceleration. Do you even live in the United States? Would the gang bangers and their cherry bombed Civics would go along.

Complain to Ralph Nader about vehicle weight. We have now mandated airbags, 35mph crash etc etc. All good things admittedly that unfortunately translate into a lot of weight. We should also mandate that everyone remove all their radios and speakers (consumes electricity and adds weight), Certainly no airconditioning (I don't really care about people in Florida/Arizona (I live in Ohio - only 3 months of hot weather, No power steering and certainly no tilt or telescope, Everyone should go back to 13" tires with steel wheels and no hubcaps....

Let's just invite the Soviets to plan our economy! We can all drive Ladas (1974 Fiats for those familiar, kind of like a Yugo).

Also note in the article that Toyota is not the most efficient in large vehicle category, GM is the leader.


See link on article for vehicle weight:


Roger's idea is sensible if the engine is a turbo - for the added torque. However, he doesn't take into account the brilliance of the auto marketers. They'd respond by making the ownership of a slow vehicle seem sexy. Then they'd respond by making the ownership of two slow vehicles seem as if you were slumming. "Don't be caught by your friends driving the same car every day. You wouldn't wear the same dress every day now would you dear?" With the entertainment media's utter obsession with wealth being ratcheted up each and every year (witness Disney), there's no limit with what they can do to distort the people's passion for acceptance to achieve their own goals - namely to separate us from our hard earned money. The bottom line for auto manufacturers has little to do with selling efficient vehicles. It has everything to do with sexual imagery; and imagery can and is manipulated by these companies and their media servants every day.

The solution lies in a universal, worldwide carbon tax. The solution would be helped enormously by a US president who daily advocates for efficiency, and by a US congress which holds the media's feet to the fire to encourage the association of efficiency with sexiness, and inefficiency with ugliness. If Fox won't play along, decertify them. That would quickly put the media where they belong, at the service of the people.

fred schumacher

When I was a millwright we used to have two jokes when things didn't go right: "Don't force it, get a bigger hammer," and "Always use the right tool. Make sure you have the right size crescent wrench when you pound on something."
Behavior and morphology are the two key problems in American automotive use and design. We use the wrong tool for the task, on average requiring 4,000 pounds of machine to move a 200 pound payload. In Europe, which has expensive fuel, fleet fuel economy is nearly twice as high as in America, but transportation utility and safety is not reduced. In America we tend to buy a vehicle for its ultimate use and then actually use it at a very low duty rate. For example, you get a pickup to pull a trailer six times a year and then commute with it daily. That's not a good use of mass.
American vehicles, whether built by American or other nations' companies are extremely inefficient from a weight and size utilization standpoint. The original Austin Mini had an 80% space utilization efficiency. Only 20% of the volume of the car was taken up by mechanicals. Nobody comes close to that today.
At any time, nearly 90% of the vehicles on the road are traveling with one occupant. We need small, safe, inexpensive "go-fer" commuter vehicles which coddle one passenger, maybe two, because most of the time that's all we need. The back seat might as well be a plank, for all the use it will ever get. The utility or mega-passenger vehicle we occasionally need could be leased as needed and not driven on a daily basis. This would simplify the problem of increasing fuel efficiency. We would not then have the near impossible task of getting 80 mpg out of a 4,000 pound vehicle.

Learn to use parsimony as a problem solving tool. The auto industry is addicted to complexity.

"Non sunt multiplicanda entia praeter necessitatem."


The original early 1960's BMC Mini Cooper that weighed 1300+ lbs. was the best car ever design for passenger space / car size and performance with 45mpg economy. Plus you had equal or better handling than nearly any popular sports car at that time.

Harvey D

fred schumacher;

Using the right tool for the job makes sense but does not seem to apply to personnal transportation vehicles in USA/Canada.

My car must be bigger, faster and have better accelleration (and even nosier) than yours are more important. That's what we've been brainwashed to believe for many decades. Undoing that is not easy. The vroom-vroom society is part of our acquired addictions and culture.

Using smaller, lighter, more efficient, quieter, more aerodynamic PHEVs and BEVs represents a major behavior change for many. Our young drivers will certainly find ways to add artificial noises reminiscent of the noisy ICE days.

I (and many others) can't wait for the day when noisy inefficient polluting ICE motor-bikes, cars, a light trucks are replaced with quiet extended electric range PHEVs and BEVs.


I’m absolutely horrified by the number of control freaks on this board, “Mandate”, “Force”, “Regulate”, sounds like the old Soviet Union or Communist China.

A carbon tax is the way to go, that way everyone pays for what the use and emit. CAFE was, and still is, one of the worst possible ways to reduce fuel consumption.

Why does it bother so many of you that other people choose to drive and pay to buy, insure and fill with fuel, large vehicles? It doesn’t bother me, even though I don’t own any large vehicles. What bothers me the most are regulations and limitations on my choices and freedoms?

Live Free or Die!



I would still have to have a vehicle with 3 or more seats even though I only utilize those seats 3.5 days a would most people with children.

Get a second car? Hmm, that would be nice if the cost of the 4 seater and 1-2 seater put together equaled the cost of my current $15,000 4 seater (considering all new prices for every vehicle). Now I would also have to find a place to park my second car since every apartment in the city (other than the very wealthy places) offer only one parking spot. Perhaps I should move out of the city and add 10-15 miles to my 2 mile commute so I can purchase a home or find apartments with more than one parking spot so I can have one ultra-efficient 1-2 seater vehicle.

What you offer does not sound very practical to me and everyone living at my apartments with children.

Roger Pham

Thanks, Cervus and John for your supportive comments of my low-tech solution.

You have a good point regarding a heavier-duty cycle vehicle will need a more beefed-up engine for durability, for example, a 2.5-liter 4-cylinder 120-hp diesel engine instead of a 1.8 liter. The low torque is not a problem, as it can be remedied thru proper gearing, for example, a six-to-eight-speed transmission. Surprisingly, a 120-hp engine can pull a boat or a trailer up a 7-degree grade just fine, even though the owner must buy a "towing" package with larger radiator, oil cooling radiator, and a transmission fluid cooler.


Thanks for your feedback as well. We are facing a looming crisis in a near future. As such, it calls for drastic measures, just as in WWII, there was rationing of every daily-essential items, from gasoline to tires to cigarettes to flour, etc. That was how the war was won. Now, we have an equivalence of war against global warming and against the disruption of peak oil.

A slower vehicle's acceleration will have negligible impact upon the total trip time or commuting time, but will have tremendous effect upon vehicular fuel economy. You can raise the engine's operating thermal efficiency from 20% to 30%, thereby achieving a 50% improvement in mpg while saving cost and weight at the same time by such a low-tech practice of engine-downsizing.

We need to put less engineering capacity onto making the huge petroleum-burning engines more efficient, by simply using smaller, simpler and cheaper engines, while devoting our engineer power on designing and building facilites for making synthetic fuels from solar and wind energy, and by making engines or FC that can run on synthetic fuels such as H2, methane, NH3, etc. This will take trillions of dollars of investment, and will create a lot of technological and manufacturing jobs, but will be a sustainable solution.

You are right about the marketer's tremendous power to influence purchasing decision. But, if people are still going to buy bigger vehicles, they will be more efficient with engine downsizing. The carbon tax is exactly what will be needed, but may be the word "tax" can be change to "environmental [restoration] fee" for users, or something more soothing, since politicians don't like to raise taxes!



You'll find that making peak oil or global warming the "equivalence of war" will be a very hard sell to the public. As pressing as these matters are, I don't think they merit a war footing, which itself implies a whole bevy of social controls, especially the rationing you mention.


Wow, just Wow,

I'm with Yuka, some of you folks scare me.

A carbon tax would not do what you want it to do. It would most likely do more damage to the Economy than serve any green proliferation.


Let's just invite the Soviets to plan our economy!

God, there's some stupid people who comment here.

Jim G.

From some of the blather here, you'd think someone was proposing gulags and chain gangs. 35 miles per gallon average, that's all that's been floated in DC. Very modest, very acheivable, very overdue.


jack and Jim G:

In the very next post, JC proposes:

If Fox won't play along, decertify them. That would quickly put the media where they belong, at the service of the people.

Government control of media, if they don't toe the line. A rather authoritarian viewpoint, don't you think?


What are people going to tow their, snow machines/boats/4 wheelers/campers with? Last time I checked, banning vehicles capable of towing large loads is limiting freedom of choice. Or would you also ban fossil fuel consuming toys?

I actually don’t own or use any of the above toys and own relatively efficient vehicles. I just can’t tolerate being told what to do. I’ll do what I want, when I want, with whomever I want to do it with. The left seems to agree with freedom of choice in certain areas (interpersonal relations and consumption of various herbs and pharmaceuticals), but they seem to have a real problem when people exercise their freedoms while consuming resources other than herbs or bodily fluids. I’m a relatively pure libertarian, and am appalled by those on the left and right who would severely limit some freedoms, while encouraging self destructive excesses in other arenas.

Would you ban downhill skiing, my favorite winter sport because it wastes energy and contributes to climate change? Surely the electricity and water for lifts and snowmaking are a silly waste of resources just so folks like me can slide down the slopes. You can argue that owning a 300 HP boat and towing it with an Expedition is a self destructive extreme. But that’s the problem with all command and control solutions like CAFE, someone’s excessive extreme is someone else’s favorite recreational pursuit. Again, this is why taxing carbon, or whatever you are trying to reduce the use of, is the simplest and best solution.

Jim G.

Well, for the record, Cervus, I'm not in favor of that, and casually assuming that the large group of people supporting 35 mpg CAFE would like that is a ridiculous smear.

Notice how the auto industry PR regularly ducks behind the consumer. "The customer made us do it!" The consumer is effectively the human shield shoved in there to rhetorically protect Detroit from attack on the points where its policies are most silly and backward and indefensible.

It's from this first obfuscation that the second one comes: that having automakers take even the most paltry efforts to improve fuel economy somehow restricts consumers' freedom. CAFE standard increases are about air quality and fuel use.

There is no reason in physics that a large, strongly built car cannot also be a lot lighter than is made now. The minute these regs are adopted, the auto companies will do the same thing they did when seat belts and airbags came in, they'll adopt them, adapt to them, and they continue selling their cars and making money.

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