Shortfalls in mpg occurred in 90 percent of vehicles Consumer Reports tested and included most makes and models.

For years, automakers have been criticized for producing vehicles that get so-so gas mileage. But as gas prices climb and consumers seek more miles per gallon, it turns out that fuel economy is much worse than it appears—50 percent less on some models, a new Consumer Reports analysis reveals.

Drivers who track their own fuel economy have long known that their results seldom match the gas mileage claimed by the Environmental Protection Agency on new-car stickers. Our study, based on years of real-world road tests over thousands of miles, quantifies the problem across a wide swath of makes and models.

We compared the claimed EPA fuel economy with the mileage per gallon we measured for 303 cars and trucks for model-years 2000 to 2006. Our selection represents a good cross-section of mainstream, high-volume vehicles. We looked at city, highway, and overall mpg.

Highlights of our study:

  • Shortfalls in mpg occurred in 90 percent of vehicles we tested and included most makes and models.
  • The largest discrepancy between claimed and actual mpg involved city driving. Some models we tested fell short of claimed city mpg by 35 to 50 percent.
  • Hybrids, whose selling point is fuel thriftiness, had some of the biggest disparities, with fuel economy averaging 19 mpg below the EPA city rating.
  • The EPA ratings are the result of 1970s-era test assumptions that don't account for how people drive today. Automakers also test prototype vehicles that can yield better mileage than a consumer could get.
  • Despite federal certification, it appears that U.S. vehicle fleets, all cars and light trucks produced in one model year, don't meet government fuel-economy standards. For example, fleet mpg for 2003-model-year vehicles we studied was overstated by 30 percent.

For consumers, the news means that their vehicles typically cost hundreds more per year to operate than they were led to believe. Put another way, when gas in August 2005 hit $2.37 per gallon, the mpg shortchange effectively boosted the price for some motorists to $3.13 per gallon.

For the nation, where the fleet average fuel economy is near its lowest point in 17 years, the findings suggest that the country is far short of its energy goals.

"We are concerned about the differences," Margo Oge, director of the EPA's Office of Transportation and Air Quality, said of our study. "I think we can do a better job to help consumers assess actual fuel economy."

Buy a fuel-efficient vehicle
Look for a vehicle that gets good fuel economy for its class. The vehicles listed below have provided the best and worst overall fuel economy within their class in our recent tests, and they are still sold. Some appear in more than one category, if appropriate.

Small cars (automatic transmission)
Toyota Prius44
Honda Civic Hybrid37
Volkswagen Jetta TDI34

Subaru Impreza 2.5i23
Chevrolet Cobalt23

Small Cars (manual transmission)
Honda Insight51
Scion xB32
Scion xA31

Ford Focus ZX4 ST26
Chevrolet Aveo LS27
Suzuki Forenza27

Family sedans
Toyota Prius44
Honda Accord Hybrid (V6)25
Honda Accord24

Subaru Legacy 2.5 GT Limited18

Large sedans
Toyota Avalon22
Mercury Montego (FWD)21
Ford Five Hundred (FWD)21

Ford Crown Victoria LX16
Chrysler 300C16
Mercury Grand Marquis LSE16

Small SUVS
Ford Escape Hybrid (4-cyl.)26
Mercury Mariner Hybrid (4-cyl.)26
Toyota Matrix XR (AWD)24
Pontiac Vibe (AWD)24

Jeep Wrangler Unlimited. (6-cyl.)14
Kia Sorento LX15
Jeep Liberty Sport (V6)15

Midsized SUVs
Lexus RX 400h23
Toyota Highlander Hybrid Limited22
Toyota Highlander Limited (V6)19
Nissan Murano SL19

Dodge Durango Limited 5.7 (V8)12
Chevrolet TrailBlazer EXT LT13
GMC Envoy XL SLT13
Land Rover LR3 SE (V8)13

Large SUVs
Toyota Sequoia Limited15

Dodge Ram 1500 SLT (5.7) V812
Ford Expedition Eddie Bauer12

Pickups (crew cab, 4WD)
Toyota Tacoma TRD (V6)17
GMC Canyon SLE (5-cyl.)16
Chevrolet Colorado LS (5-cyl.)16

Dodge Ram 1500 SLT (5.7)11
Dodge Ram 1500 SLT (4.7)12

Other ways to save money on auto travel

  • Be skeptical of EPA ratings. The EPA sticker can help you evaluate relative gas mileage among vehicles, but not absolute mpg. Until the EPA ratings are made more realistic, discount the EPA sticker numbers for city travel as follows: conventional cars and trucks, 30 percent; larger hybrids, 35 percent; diesels, 36 percent; smaller hybrids, 42 percent.
  • Buy regular.If your car owner's manual doesn't recommend a particular grade of gasoline, fill 'er up with regular. And don't waste money on so-called gas-saving devices; our tests have shown that they don't work.
  • Walk, bike, or "chain." Fuel economy is worst on short trips. These trips also create the most exhaust emissions and cause the most engine wear. Half of all car trips are under six miles, within walking or biking distance. If you must drive, "chain" several errands into a single trip on a warm engine instead of making separate short trips throughout the day.
  • Avoid highway drag. At highway speeds, where fuel economy is best, more than 50 percent of engine power goes to overcoming aerodynamic drag. Try not to add to that drag by carrying things on top of your vehicle. A loaded roof rack can decrease a car's fuel economy by 5 percent. Even empty ski racks waste gas.
  • Keep your vehicle in top shape. A poorly maintained engine can cut gas mileage by 10 to 20 percent. A clogged air filter can cause up to a 10 percent increase in fuel consumption. Underinflated tires require more energy to roll and can reduce fuel economy by 5 percent. Follow the maintenance schedule in your owner's manual, and keep the tires properly inflated.
  • Drive smart. As much as possible, avoid hard acceleration and braking. Once up to speed, maintain a steady pace in top gear; varying your speed a lot wastes fuel. A vehicle's gas mileage decreases rapidly at speeds above 60 mph. With most gasoline engines, it's more efficient to turn off the engine than to idle for any longer than 30 seconds. If you have air conditioning, use it sparingly.

The full Ratings and recommendations for more than 200 vehicles, along with the latest information on thousands of other products and services, are available to subscribers. Find out how to subscribe today.