The government has introduced new fuel economy ratings that are more accurate. We make them easy to understand.
By Bill Howard
Three decades after the federal government first required automakers to post test-based reports on the mileage their cars and light trucks get, there’s a new set of rules intended to be more reality-based and reflect the fuel economy you actually get. The result is that 2008 cars, vans and SUVs will typically be rated at 2 to 3 mpg less than the same leftover 2007 vehicles still on dealer lots. Relax — the automakers are just following government orders. The mileage you get should be unchanged.
Fuel economy ratings date back to the Vietnam War-era oil embargo of 1973 that made gasoline scarce and led Congress in 1975 to require fuel economy ratings using government-standardized tests. Unfortunately, the previous tests were little changed since 1985 even though the way we drive has changed significantly. Then, speed limits were 55 mph; now they’re often 65 mph and sometimes 70, 75, or 80. Also, the average vehicle weight has increased from about 3,200 to 4,000 pounds.
Two government bodies in the U.S. Department of Transportation are involved in determining your car’s mileage rating. The National Highway Traffic Safety Administration (NHTSA) sets the standards and the U.S. Environmental Protection Agency (EPA) performs the calculation. EPA calculates both the fuel economy numbers that appear on new car window stickers and an official average for automakers’ fleets, called CAFE, or corporate average fuel economy.
For cars, the CAFE average is currently 27.5. For light trucks that weigh less than 8,500 pounds, it’s currently 20.7 mpg, rising to 22.5 mpg, 23.1 mpg and 23.5 mpg in 2008, 2009 and 2010 respectively.
A gas guzzler tax kicks in for vehicles that fall at least 5 mpg short of a fuel efficiency standard that is based roughly on the CAFE ratings. The penalty amounts to about $550 for each mile per gallon under 22.5 mpg and is calculated in 1 mpg bands, ranging from $1,000 for vehicles rated 21.5 to 22.4 mpg, through $3,000 for cars getting 16.5 to 17.4 mpg, up to the maximum $7,700 for vehicles getting less than 12.5 mpg.
While the automaker does pay the fine, it is passed along to the buyer in the price of the car in the form of a gas guzzler tax. But there are loopholes you can drive a truck through, particularly the exemption for (at least in name) light trucks with a loaded weight rating of more than 8,500 pounds. That’s why some Hummers, including the biggest Hummer, the H1, escape paying the gas guzzler tax.
With the popular Ford Mustang, including some V8 models that get 19 city, 28 highway, there usually isn’t a gas guzzler tax. However, high-performance addicts who opt for the top-of-the-line Mustang 428R will pay a $1,000 gas guzzler tax as mileage drops into the mid- to high teens.
The least fuel-efficient car sold in 2008, getting 8 mpg city, 13 mpg highway (10 mpg overall on 2008 ratings), is the 12-cylinder Lamborghini Murcielago. But at $345,000, the $7,700 gas guzzler tax — roughly equal to a 14 mpg shortfall at $550 per mpg — is a rounding error. If it’s any consolation, exotic sports cars are rarely driven more than 2,500 miles a year, so they don’t burn that much fuel on an annual basis.
Testing, Testing
Tests are run indoors on giant rollers, called dynamometer wheels, which are delicate devices, so the average acceleration was about what you’d accelerate during a driving test — gently. In the previous tests, most accessories were switched off. Now the tests use quicker acceleration similar to how the average driver starts off, the air conditioner and accessories are on, test speeds go up to 80 mph, and the test chamber temperatures include middle-of-summer and dead-of-winter extremes.
The EPA says the average vehicle’s test results will decrease about 12 percent, but the drop-off could be up to 30 percent. On a vehicle getting 25 mpg, 12 percent is 3 mpg. For the 2007 fuel-economy champ Toyota Prius, rated last year at 60 mpg city, a 12 percent drop would be 7.2 mpg, while the actual rating is 51 mpg city, a 15 percent drop would be 9 mpg. Its highway mileage falls only 3 mpg, or 7 percent, from 48 mpg to 45 mpg.
In general, the EPA says, smaller cars are more affected by the new ratings because they work relatively harder. And high-mileage cars seem to be affected more because the same 15 percent drop for a Prius from 60 to 51 would be the same ratio as a 20 mpg car going to 17 mpg. Hybrids are hit hardest because the regenerative braking that recharged the big onboard storage batteries is less efficient recapturing energy under sharp braking conditions.
Also, don’t just think about miles per gallon, but the total cost of filling up your vehicle. Compared to regular fuel, premium adds 10 to 15 cents per gallon and that raises your gasoline cost per mile by 5 to 10 percent.
10 Fuel Economy Tips to Improve Vehicle Mileage
Here’s how you can get the best possible fuel mileage without investing too much time and effort.
- Don’t accelerate too slow or so fast you chirp the tires or annoy nearby motorists. In most cars, brisk acceleration may actually save a bit of fuel because of the resistance, called pumping losses, as air coming in the engine has to fight its way past the metal throttle butterfly, which acts like the open-and-close flap on a heating duct.
- Use cruise control on the highway. It may be smoother than your own accelerating.
- Keep your tires inflated properly. (Yes, you’ve heard this before, but that’s because it saves fuel.)
- While many driving-advice articles say to get a tune-up, most cars go 100,000 miles without the classic tune-up. However, that doesn’t absolve you of replacing the air filter at least yearly.
- Practice prudent speeds on the highway. Above 50 mph wind resistance plays a bigger part in fuel economy. Don’t stray from the posted speed limits, because driving much faster or slower than other cars creates a hazardous speed differential.
- Use the thinnest weight motor oil safely recommended by the automaker. Often, that’s a 5W30 oil, whereas 15 years ago, it was 10W30.
- Take extra weight out of the car. Automakers spend millions to save 100 pounds, but you can take unneeded weight out of the car for free and save 1 to 2 mpg by removing items such as cases of bottled water, sports bags and golf clubs. Anything unrestrained in the cockpit is also hazardous in a panic stop or crash.
- Remove the ski or bicycle rack when not in use. The drag at highway speeds can cost 1 to 2 mpg.
- Avoid convoys on interstates that bunch up and force you to slow down, speed up, slow down, speed up.
- If you own more than one car, whenever possible, drive the one that gets the best mileage.
Fuel Efficiency: By the Numbers
These are the most and least fuel-efficient cars sold in the United States for 2008, ranging from two-seaters to midsize station wagons. For more details, visit www.fueleconomy.gov.
Most Fuel-Efficient Cars
EPA Size Class/ Transmission/ Fuel/ City MPG, Hwy MPG
Two-Seaters
Audi TT Roadster
4 cyl, 2 L/ Auto (6)/ Premium/ 22, 29
Minicompact Cars
Volkswagen New Beetle Convertible
5 cyl, 2.5 L/ Manual (5)/ Regular/ 20, 28
Subcompact Cars
Scion xD
4 cyl, 1.8 L/ Manual (5)/ Regular/ 27, 33
Compact Cars
Toyota Corolla
4 cyl, 1.8 L/ Manual (5)/ Regular/ 28, 37
Midsize Cars
Toyota Camry Hybrid
4 cyl, 2.4 L/ Automatic (CVT), HEV/ Regular/ 33, 34
Large Cars
Hyundai Sonata
4 cyl, 2.4 L/ Manual (5)/ Regular/ 21, 31
Small Station Wagons
Pontiac Vibe
4 cyl, 1.8 L/ Manual (5)/ Regular/ 26, 33
Midsize Station Wagons
Volkswagen Passat Wagon
4 cyl, 2 L/ Manual (6)/ Premium/ 21, 29
Least Fuel-Efficient Cars
Two-Seaters
Lamborghini L-147/148 Murcielago
12 cyl, 6.5 L/ Man (6)/ Premium/ 8, 13
Minicompact Cars
Porsche 911 Turbo Cabriolet (tie)
6 cyl, 3.6 L/ Auto (5)/ Premium/ 15, 23
Subcompact Cars
Mercedes-Benz CLK63 AMG
8 cyl, 6.2 L/ Auto (S7)/ Premium/ 12, 18
Compact Cars
Bentley Azure
8 cyl, 6.7 L/ Auto (S6)/ Premium/ 9, 15
Midsize Cars
Bentley Arnage
8 cyl, 6.7 L/ Auto (S6)/ Premium/ 10, 15
Large Cars
Bentley Arnage RL
8 cyl, 6.7 L/ Auto (S6)/ Premium/ 9, 15
Small Station Wagons
Audi S4 Avant
8 cyl, 4.2 L/ Man (6)/ Premium/ 13, 20
Midsize Station Wagons
Mercedes-Benz E63 AMG
8 cyl, 6.2 L/ Auto (S7)/ Premium/ 12, 18
Bio: Bill Howard is an experienced automotive writer and the editor of TechnoRide.com, the car technology site produced by Ziff Davis. Previously, he was PC Magazine’s executive editor. Howard is also vice president of the International Motor Press Association.
The views and opinions expressed in this article are solely those of the author and not necessarily those of Progressive Casualty Insurance Company or its affiliates.