The Myth of Ever Increasing Fuel Economy

American Thinker ^ | May 23, 2009 | R.H. Higgs

[neverdem]

Two months ago I did what most environmentalists would consider unthinkable. I purchased my first 4X4 vehicle.

Since I wasn't planning on using it as my primary vehicle, I wasn't willing to shell out the multiple thousands of dollars involved in purchasing new. The logical choice was to pick an early 1990's model which was still in good condition. I found one with electronic fuel injection, A/C, and power everything. Even though it's verging on its twenty year birthday, it is still a sharp looking vehicle in very good condition.

So, imagine my surprise at the responses of my friends and acquaintances.

The comment, "You bought what? What a gas guzzler!" was generally quickly followed up by, "you should have purchased something newer for better gas efficiency."

Does that really make sense? Have vehicles improved so drastically compared to older models? Would I be better off tripping the parking brake on my sweet ride and pushing it over a cliff? While many environmentalists would automatically agree with that sentiment, are the savings actually that significant?

I was nursing a little bit of insecurity about my investment, so I went to the EPA's fuel economy website in order to get some hard numbers. I found something very surprising. When comparing my 1993 4X4 to a current offering with a similar size engine block, transmission and carrying capacity, I found the newer model exceeded my fuel economy by an astonishing: 1 MPG.

"No kidding? Whew, I can live with a loss of 1 MPG. I dodged a bullet there!"

The story doesn't end yet. On May 19, 2009, the AP carried the story of Barack Obama and his new "tougher" fuel economy standards. These new standards would require passenger vehicles to achieve 39 MPG and light trucks, 30 MPG. This would result in an overall fleet average of 35.5 MPG. While the media lovingly touted these new standards as progress, I went back to the numbers.

Knowing what I did about my 4X4, I decided to compare the economy of other typical vehicles through http://www.fueleconomy.gov/. In comparing the numbers, I tried to use similar engine sizes, transmissions and other relevant equipment in order to determine whether the evolution of a vehicle over twenty years improves the fuel economy on any comparable newer model. The results are an eye opener.

Toyota Corolla

Records on this vehicle go all the way back to 1985. Throughout the time frame of 1985-2009, it was offered in front wheel drive and a four speed automatic transmission. The only change came in 1993, when the engine displacement was increased from 1.6L to the current 1.8L.  

This is interesting isn't it? The trend of the average fuel economy climbs only slightly between 27 to 30 MPG. Maximum highway fuel efficiency peaked in the early 2000's and then fell back around 35 mpg for the remainder of the decade, essentially unchanging for 10 years. Overall, fuel efficiency gain for highway driving increased only about 10%, city had an increase of 8% both over the period of 24 years.  Typically the auto industry redesigns their vehicles every four years or so, therefore this scale represents at least five separate design cycles of the same model.  Since the Corolla is on its 10^th generation and this chart started in the middle of the fifth generation, it seems Corolla is reflecting typical industry practice.

Considering this class of vehicle has an emphasis on fuel economy, it seems reasonable to expect significantly larger gains, wouldn't you?

Ford Taurus

This four door sedan was easy to compare model years. During its production run of 1989 to 2007, it was offered with a 3.0L V6 engine, a four speed automatic transmission and front wheel drive. In 2008 the base model engine displacement increased to 3.5L.

Even considering the multiple design cycles over twenty years (five for Taurus) there is little to no change in fuel economy. It seems reasonable to assume the engine systems were improved over this 20 year cycle. Including all technological improvements between 1989 and the present, the average fuel economy has continually hovered around 21 MPG. With a trend like this, it seems extremely difficult to nearly double the fuel efficiency on a similar platform in only seven short years.

Ford F-150

Looking through the EPA entries, the high output model of this truck has had more configuration changes than the other vehicles. It makes an interesting point.

In 1985, the truck was offered with a 5.8L V8 and 3 speed automatic transmission. In 1990 one change was made, the 3 speed was discontinued and replaced with a 4 speed automatic.  In 1997, the engine displacement was reduced to 5.4L and finally for the 2009 year, the engine was again reduced to 4.6L.

Why is this interesting?

Notice at 1990, when the transmission was upgraded, the highway economy jumped. This is to be expected, because higher gears allow the engine to be more efficient at higher speeds. Again, in 1997, you see another slight trend upward with the reduction of the engine size. Yet again, in 2009 there is a slight jump with the reduced engine size.

However, even accounting for the nearly 30% average improvement in fuel economy over 24 years, it seems like the average 30 mpg mark is a long way off. In fact, even though engines cannot be continually refined to ever increasing heights of efficiency, let's assume they do for a moment. Let's also assume this historical data is representative of the trend for this type of vehicle. With these assumptions, if the average economy is 12 mpg in 1985 and 16 mpg in 2009, at the current rate of progress, it would be 2093 before this particular model of light truck would have a fuel efficiency of 30 mpg.

This is not to impugn the automotive industry, if it were possible to design an engine that achieved 200 mpg, I have no doubt they would have succeeded by now. The automotive market is competitive like any other and companies are always trying to maintain an edge on their competition.  Achieving any exponential increase in fuel economy would make them market leaders in a moment. Unfortunately, internal combustion is a mature technology which we understand very well. Because the basic concept has stayed the same for a hundred years, engineers spend their time making minute tweaks in order to achieve gains of one type or another.  These gains are not mutually inclusive. An engine sacrifices power and torque for fuel efficiency or vice versa.

Engineering is the science of making compromises in order to create a product which functions. If an engineer increases the gearing in a transmission, the vehicle gets heavier; at a certain point, increased gearing brings no fuel efficiency benefit thanks to the extra weight. If an engineer decreases engine displacement, efficiency will increase to a point, then decline as the power to weight ratio becomes unfavorable. This will continue right up to the point where the vehicle is unable to move its own weight.

Another option is to reduce the weight of the vehicle to get the gains Obama so desires. Continuing down this path, the automobile quickly becomes a motorcycle.

As many others have pointed out, this results in designs where a vehicle becomes lighter and proportionally less safe as the inertia is decreased.

That's obvious, but not the point.

The point is, since the 1970's fuel economy has become one of the yardsticks by which all vehicles are measured. Arguably, to some it has become the most important. People seem to naturally assume that a new vehicle is going to perform yards above that of its predecessor. Hence, there becomes an expectation that fuel economy can and will always increase. Looking at the plotted fuel economies of the above representative vehicles, this expectation doesn't show true.

We're expecting miracles from a technology which has truly reached its limits. This is unreasonable. For each class of vehicle, the unique characteristics of its mission almost appear to dictate its fuel economy. An economy car isn't comfortable for carrying a family of five and a sedan will never carry a couple yards of topsoil for your garden. The sedan will never rival the economy car in fuel efficiency because it has different requirements it has to meet.  From the buyer's standpoint, within vehicle classes, a 10 year old car is economically the same as a new one.

By proposing a set limit for economy on all classes of passenger vehicles, Barack Obama has basically said one of two things: In 2016, he wants only economy cars to be sold in the US or he is instructing car companies to squeeze gas from a stone. Since he cannot change the laws of physics, I envision the date those proposed standards take effect will either be repealed by the next administration, or continually be delayed.

This is just another dictate similar to all the rest of Obama's plans: not based in reality, but wishful thinking.

Note: Many will note I only compared regular gas vehicles and did not include hybrids and alternative fuel vehicles in the mix. Neither type of vehicle has enough fuel efficiency history to establish a trend. At most, the oldest models of hybrid vehicle are currently on their second design iteration and alternative fuels have not yet been shown to be viable. Regardless, there is no reason for me to believe that any of these variations on the internal combustion engine are immune to the same constraints that govern modern automotive design.

[Malsua]

I have a question.

Using that site http://www.fueleconomy.gov/ are the fuel economy numbers adjusted to normalize pre/post 2008 testing standards?

For 2008 and newer models, the testing standards are different and tougher. Sort of like the old Horsepower ratings on muscle cars to today’s cars, you can’t compare the two, it’s not apples and apples. A car that was rated to have say 22highway in 1993 probably would rate 19 highway or so for 2009.

[bert]

Then there is ethanol. When ethanol is blended into the gasoline the mileage decreases. That is, it takes more fuel to travel a given number of miles on ethanol blend than it did on undiluted gasoline. If the amount of ethanol added is 10% as it is, and the decrease in mileage is 15%+ as actually is, the ethanol actually increases the amount of gasoline consumed.

The net result is an increase in the amount of imported gasoline as a result of blending in ethanol.

[narses]

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Obama Says A Baby Is A Punishment

Obama: “If they make a mistake, I don’t want them punished with a baby.”

[conservatism_IS_compassion]

Every time you slow down, it makes more juice!

So it only can re-use the energy of slowing down?

How does that help HIGHWAY mileage?

Obviously if you are on the highway, you do very little braking compared to city driving, and the benefit of regeneration of braking energy is de minimus. AFAIK hybrid vehicles attain much of their efficiency by using the electrical generator and battery to control the speed and power output of the gasoline engine to allow it to operate at the RPM and power at which it is most fuel-efficient.

A primary disadvantage of the diesel engine is the relatively low RPM limit imposed by the massive pistons and connecting rods needed to withstand the "diesel knock" which occurs in normal operation. And although the diesel is so much more expensive and more efficient than the gasoline engine that it would be less necessary, I keep expecting someone to come up with a diesel/electric hybrid to minimize the RPM sensitivity of the diesel by holding RPM constant. That could be one response to the Obama efficiency mandate . . .

[Hardastarboard]

This is a more affluent country than it was 25 years ago.

Good post. You made some very solid, succinct, inarguable points. 0bama is about to take the one above away from you.

[Hardastarboard]

I used to go to junkyards quite a bit. That can be a real eye-opening exercise. You see some vehicles that look like they’ve been smashed by the hand of God.

[Taxman]

That is what I have noticed — roughly a 15% reduction in mileage with 10% ethanol.

I hate the stuff, and I am extremely prejudiced against those idiots who forced that crap on us!

Every chance I get to bad mouth an environmental whacko, I do so.

They and the PC Police will be the absolute ruination of this country.

More to the point, I’m keeping my 1990 Cadillac Fleetwood Brougham. When it needs repairing, it’ll get repaired.

I’m averaging 17.8 mpg over 126,600 miles of combined highway/city driving, and 21 mpg on the highway is not at all uncommon. And that is with that #%&@ing ethanol!

Plus, it is a large, comfortable car. A keeper!

[WVKayaker]

Just google diesel, hybrid, europe!

...The BMW 335d clean diesel sedan arrives in showrooms this month, followed by the BMW X5 clean diesel SUV in January. Before the public has had a chance to decide on the value equation of its first two luxury diesel vehicles in the $40,000 to $50,000 price range, BMW is now considering an even more expensive clean diesel 7-series sedan.

The European 730d is powered by a turbocharged six-cylinder diesel engine and yields 45 miles per gallon. Even with this impressive fuel efficiency, BMW is gambling on a much-improved economy, and the price of gasoline heading back up, by the time the diesel 7-series would arrive sometime in mid-2010.... http://www.hybridcars.com/buying-decision/bmws-7-series-diesel-possibly-headed-us-25304.html

[nascarnation]

Don’t be fooled by the miles per gallon stats game.

Sure going from 10 to 20 saves a LOT of money on fuel.

Going from 20 to 30 a bit more.

But beyond that, the cost / savings ratio is really bad.

[WVKayaker]

Don’t be fooled by the miles per gallon stats game.

Sure going from 10 to 20 saves a LOT of money on fuel.

Going from 20 to 30 a bit more....

Maybe I missed the math class that taught that 50% was more than 100%...

I understand your gist, but when gasoline gets back to $4+, and you MUST drive, a little can be a lot!

[Reeses]

if it were possible to design an engine that achieved 200 mpg

Theoretically fuel efficiency approaches infinity as speed approaches zero, so it is possible to get 200mpg however the vehicle would have to move at turtle speed. Air conditioner, fan, radio energy use though increase with travel time so this limits fuel efficiency in the real world.

[slowhandluke]

Using engines similar to a 1000cc motor racing cycle

Even today's small hybrids use bigger motors than that. You aren't going to replace a 5L (~320ci) engine with a 1L engine plus a small electric motor. It turns out that for space efficiency and distance traveled, you can't beat a tank of gas and an internal combustion engine - except if you use diesel.

The electric engines in hybrids aren't used at highway speeds. The electric engine has an advantage in the stop and go, and low speed regimes where speed changes a lot. On the open road, the inefficiencies involved in running the gas engine through an alternator to drive the electric motor mean that you just run the gas engine only. So, if the gas engine isn't big enough to drive the entire load at highway speeds, it isn't big enough.

And your example of a racing engine fails, as racing engines aren't required to meet road car emissions or noise standards. Meeting both those standards will reduce power and mileage.

[The Great RJ]

The only way automakers will reach Obama's goal is to radically redesign the vehicles. As this article so clearly points out that the CAFE standards cannot be met by incremental engineering changes in current lines.

What car makers have done in the past is a careful balance of improved fuel economy, drivability and utility. Obama's standards will throw practical considerations out the window and vehicles will be designed solely to meet fuel efficiency standards. The 30 mpg truck will by necessity have very limited cargo capacity and likely no towing ability. Many businesses as well a farmers and ranchers depend on trucks for heavy duty jobs, large load capacity and hauling trailers. Who does Lord Obama think will buy these vehicles when they cannot do the job?

[yazoo]

Any gas guzzler that can pass an emissions test does not impact the environment in any way. Environmental idiots confuse saving gas with protecting the environment. These are the same morons who think recycling paper saves rain forests.

[Don W]

Don’t confuse the issue with facts! Shady hates Fords, and therefore he owned a couple of (non-existent) Focuses (foci? LOL) in the 1990’s and they were crap. In that vein:

Every GM product I’ve ever owned has been an unmitigated pile of excrement, but until now I have refrained from posting about how utterly pathetic GM engineering and build quality has been in my experience. I’d buy a Peugeot before another CheBuPoCad. Then there’s Saturn (cars for people who hate cars).

I’ll stick with my older Fords and Internationals. Reliable, tough, and just a little quirky.

Should I decide to buy new, there isn’t one offering GM or Chrysler can make that doesn’t have the taint of subsidy and 0bama (ptui) to it. I rented a GM Envoy last January, and it wasn’t near as awful as my previous experiences with GM products, giving me second thoughts about my “Just Say No to GM” stance, and then this auto bailout occurred.

[Don W]

My ‘89 Crown Vic STILL gets 30mpg on the highway. 302/AOD, full load.

70 MPH, 30 MPG all day long while sitting in the living room. Gotta like it!

[Jeff Chandler]

70 MPH, 30 MPG all day long while sitting in the living room. Gotta like it!

I sold mine when it was approaching 260,000 miles.

I miss my boat. If I could buy one exactly like it brand new I would.

[tina07]

Oh yes, some you wonder if they got out alive. Too many crazy inattentive drivers out there. Real bad here in PA, they don’t know what that double yellow line is for, never saw so many riding the line and/or crossing it. I never had to use my horn as much as I do now.

[neverdem]

I have a question.

Using that site http://www.fueleconomy.gov/ are the fuel economy numbers adjusted to normalize pre/post 2008 testing standards?

I have no idea. Maybe it's answered by a motorhead already on the thread. I haven't finished reading it yet. I'm doing some other stuff right now.

[RipSawyer]

Regarding claimed mileage, you can’t compare 80s window sticker numbers to modern cars. The EPA changed the test to give lower results in 1984, and again in 2007. 50 then would be about 35 now.
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Who goes by window stickers? I bought a 1980 Pontiac Pheonix new and on a trip from Florence, South Carolina to Kennett Square, Pennsylvania with three adults, a twelve year old and a trunk full of luggage I averaged 34.2 miles per gallon as calculated from meticulously recorded mileage and fuel records. The car was reasonably roomy and comfortable for the trip,(I am 6’ 4” and weighed about 220 at the time) it was air conditioned and I drove at interstate speed. Why is it such a big deal to find a car that will do the same thing today, almost thirty years later?