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May 23, 2009

Efficiency Breakthrough: Small Cars With Small Engines

Fuel efficiency is an expensive option. Most of it comes from cars that are smaller, lighter, less powerful, and more dangerous in a crash.

Miles/gallon "mpg" is misleading. Gallons used per 100 miles "GP100" is a better indicator of savings. Going from 20 to 25 mpg (from 5 to 4 GP100) saves the same amount of gasoline as going from 25 mpg to 33.3 mpg (from 4 to 3 GP100).

To save an additional 1 gallon/100 miles, the car would need to get 50 mpg, a very difficult engineering challenge at high cost.

Dear Barack: Does your Chrysler 300C get 35.5 MPG?
05/22/09 - DirectorBlue.Blogspot.com
(Via RiehlWorldView)

From Car and Driver, May 2009 by Steve Siler and Mike Dushane:

[edited] Obama's proposed requirement raises fuel economy standards (CAFE) about 5% each year until 2016.

Trucks must go from 23 to 30 mpg (30% better miles per gallon), and passenger cars must go from 27.5 to 39 mpg (42% better), to achieve 35.5 mpg averaged overall.

Senators say these goals have been met in Europe. But, car for car, European vehicles aren't much more efficient than current US vehicles.

Take the Ford Focus sedan, a car that is about the same size in the US and in Europe.

  • The US basic Focus sedan costs $15,000, has a 140 hp engine, and is rated at 28 mpg combined by the EPA.
  • The German basic Focus sedan costs $20,000 (plus 19% tax!), has only a 79 hp engine, and would be rated at 30 mpg combined by the EPA (based on usual differences between US and EU test numbers).
Europeans pay $5,000 more for 56% of the power, and gain 7% fuel economy (the car travels 7% farther on a gallon of gas).

So, why is Europe's fleet so much more efficient overall? Europeans buy much smaller cars.

The Focus is one of the tinier mass-market cars sold in the US today, but it is a family car in Europe. The average European buys a car a few sizes smaller than a Focus. About one-half of Europeans buy diesels, which consume around 30% less fuel. Europeans have parking space limitations and small roads. If they drove the long distances we do, they likely would drive bigger cars, as we do.

Engineering options to meet the proposed requirements are costly.

  • Diesel engines led the efficiency revolution in Europe, but they are dirty. New particulate limits require thousands of dollars in extra costs for NASA-level catalytic converters.
  • Hybrid technology increases efficiency 30%, not the required 35%, and costs $4,000 - $10,000 according to vehicle size.
  • The GM Volt has an extended-range electric powertrain. GM does not give a cost, but industry sources estimate $10,000 more for a small car, with higher costs proportional to vehicle size.
  • Lightweight materials can help a few percent, but they are already in use and greater use would yield diminishing returns and massive cost.

The Obama administration estimates $1,300 more per car to meet mileage goals. This is absurd. Consumers would need to pay at least that AND move down a few vehicle sizes.

General Motors Vice Chairman Bob Lutz predicts that the new CAFE standards will increase car prices by $4,000 - $10,000 per vehicle, averaging $6,000.

(Car and Driver continued ...)

Will US consumers buy these smaller cars?

The few such vehicles available today don't sell in large quantities because of their small size, poor performance, and high prices.

Sales of the Toyota Prius and other hybrids briefly shot up when gas cost $4 a gallon, but sales dropped with falling gas prices. Prius sales fell so much, beyond the overall declining market, that Toyota last year halted construction of a Prius factory in Mississippi. The best-selling vehicles in the US this year are the Ford F-150 and Chevrolet Silverado pickup trucks. Nobody is stopping these people from purchasing a Prius instead.

The Obama administration claims the new requirements will save 1.8 billion barrels of oil over seven years (0.26 bbl/year). This assumes that people will want to buy new, expensive, tiny cars. If people instead purchase bigger, cheaper, used cars, there will be no reduction in oil consumption. Those used cars are the same "guzzlers" we are driving today.

Worse, the auto industry will continue to shrink from a decrease in new-car sales at higher prices.

How Much Oil and Money Will Be Saved?

According to US Government Energy statistics, US oil consumption for 2007 was 7.55 bbl (billion barrels) (20.68 million barrels/day). The 70% used for transportation was 5.29 bbl.

The claimed savings from stricter CAFE requiremnts is 0.26 bbl/year. That would save 4.9% of transportation oil (3.5% of all oil).

Here are the personal savings for 15,000 miles/year with gasoline at $3/gallon.

    Auto Efficiency, Fuel Use, and Present Value

  Miles       Price of         Discount
  /year       Gasoline           Rate
 15,000          $3.00           10%

         Gal      Fuel    Gal     Cash     10 Yr
 MPG    Used      Cost   Saved   Saved     Value
 ---    ----    ------   -----   -----    ------
27.5     545    $1,636      0     $  0    $    0
30.0     500    $1,500     45     $136    $  838
35.0     429    $1,286    117     $351    $2,155
39.0     385    $1,154    161     $483    $2,965

Excel spreadsheet for the above figures

You save 161 gal and $483 yearly if you drive 15,000 miles and increase efficiency from 27.5 to 39.0 mpg, pricing gasoline at $3/gal.

The "10 Year Value" is what 10 years of savings are worth to you today. Saving $483 each year for 10 years at 39 mpg totals $4,830. You must pay today for the car and its technology to get savings spread out in the future. These savings are worth $2,965 to you today, if you value the use of your money at 10%/year.

Say you are purchasing a car with a 10% auto loan. Paying $2,965 more for greater efficiency would just balance the savings on gas. You would save $4,830 in gas over time, but would also pay that amount in increased purchase price and financing costs.

What if you paid $5,000 more as in Germany now, and as conservatively predicted by Bob Lutz? The fuel savings are worth $2,965 to you, so you would lose $2,035 on the deal.

We must hope that:

  • The increased cost of the car is small
  • The claimed efficiency is true
  • There are no increased expenses and inconveniences for repairing or using the new technology
  • Used-car prices will hold up if you won't be keeping the car for the full 10 years.

The Obama adminstration expects to save .026 bbl of oil yearly, which I assume means gasoline. There are 42 gallons per barrel. That is 10.92 BGal of gas. If each new car saves 161 gallons/year, this would require replacing 68 million cars, or a smaller number of cars and trucks. Trucks usually travel more miles each year than autos.

So far in 2009, cars and light trucks together are selling at the rate of about 10 million/year. So, Obama's savings would require selling roughly 5 years of total car and light truck sales as efficient, expensive, new technology vehicles. This seems unreasonable to me, and needs a detailed explanation.


These results are what you will get after paying more for a smaller, less powerful car with lower safety. Smaller, lighter cars produce more deaths in auto accidents. This doesn't seem to be included in the government's considerations.

Obama’s new cars will cost more, and might kill you
5/21/09 - Louisville City Hall Examiner by Thomas McAdam

Since CAFE passed in 1975, smaller cars have killed almost 50,000 more people than otherwise would have died on the roads, according to the National Highway Traffic Safety Administration (NHTSA).

A number of studies have documented the lethal consequences of requiring carmakers to improve fuel standards. [This results from making the cars lighter. -ag].

Gallons per 100 Miles

Buy an S.U.V., Save the Planet
06/02/2009 - Freakonomics by Eric A. Morris
[edited] We can improve fuel economy not through the onerous task of developing next-generation lithium-ion batteries but simply by getting people behind the wheels of more efficient SUV’s.

Upgrading an inefficient Range Rover SUV at 14 mpg to a more efficient RAV4 SUV at 24 mpg would save a lot of fuel. Actually, more fuel than switching from the RAV4 to the most fuel-efficient car on the market, the 2009 Toyota Prius at 46 mpg.

We have a policy option that is almost painless. Show car buyers the Gal/100 Miles figures instead of mpg. To be fair, car window stickers currently show annual estimated fuel cost. But the mpg figure takes center stage, much as it does throughout our society. Changing window stickers seems a lot easier than developing new generations of ultra-lightweight car body materials, and it could have a significant impact.

Moving SUV owners into the Prius is going to be a struggle. We should be happy if the public chooses more efficient SUV's, because the savings are still great. Consider driving 15,000 miles per year.

        Miles    Gal  /     Gal    Diff
         /Gal  100 Miles   Used   Saved
Rover     14      7.14    1,071 
Rav4      24      4.17      625     446
Prius     46      2.17      326     299

Let people motivate themselves by fuel savings within the category of car which they prefer. Don't force car purchases through mandates and tax policy. Show the savings and let consumers make the tradeoff between initial cost and future savings.

+ + + + +

A Car Wreck Made in Washington
CAFE standards have been used to protect auto unions, regardless of efficiency.

All opinions about automobiles

Correction: The first version of this post showed incorrect data for two days based on 30 mpg rather than the correct 39 mpg claimed efficiency.

1 comment :

Anonymous said...

The problem with putting the gas consumption in abstract terms is that it runs counter to how people actually experience their car's cost. They don't pull 15 gallons of gas or 300 miles from their account, they pay $50 every week or more on the gas guzzler and maybe that much in two or three weeks for the more efficient car. The people who drive those cars are well aware which is draining most of their money.

Personally, I record the mileage and gas consumed every time I fill up. Yet, I don't actually compile either statistic. I just know that if the fill light comes on before a certain amount of miles, I should see if anything is wrong.

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