Top SUVs for Fuel Economy

No organization tests every vehicle's fuel economy in real-world driving. The challenge of obtaining every vehicle early in the model year, then driving them all over a specific route under identical conditions, is insurmountable. Therefore, we have to rely on Environmental Protection Agency estimates. While you can't expect your vehicle to get the exact mpg figures supplied by the EPA, mileage estimates do let you compare vehicles.

Most Fuel-Efficient SUVs for 2006
According to EPA estimates, the following sport utility vehicles are likely to deliver the best gas mileage. They're listed in order of anticipated city fuel economy, starting with the most miserly.
Compact SUVsMPG (City/Hwy)*List Price
Ford Escape Hybrid36/31$26,900 - $28,525
Mercury Mariner Hybrid  33/29$29,225
Toyota RAV4  24/30$20,300 - $25,870
Ford Escape  24/29$19,380 - $26,680
Mazda Tribute  24/29$20,115 - $24,700
Midsize SUVsMPG (City/Hwy)*List Price
Lexus RX 400h  33/28$44,660 - $46,060
Toyota Highlander Hybrid  33/28$33,030 - $39,290
Subaru Baja  23/28$22,495 - $24,595
Toyota Highlander  22/27$24,530 - $31,860
Nissan Murano  20/25$27,600 - $31,700
Full-Size SUVsMPG (City/Hwy)*List Price
Dodge Durango  16/21$28,300 - $37,310
Chevrolet TrailBlazer EXT  16/20$25,880 - $30,230
GMC Envoy XL  16/20$27,380 - $37,600
Isuzu Ascender (7-pass.)  16/20$27,998 - $31,193
Chevrolet Tahoe  16/20$34,015 - $39,415

*EPA estimates represent the highest rating for each model. Fuel economy will vary according to a vehicle's engine, transmission, drivetrain and trim level.

Source: 2006 Model Year Fuel Economy Guide, published by the U.S. Department of Energy and the U.S. Environmental Protection Agency

EPA Estimates: A Flawed but Helpful Yardstick in Comparing Vehicles
The mileage estimates for SUVs like Toyota's Highlander Hybrid do not reflect road tests of the vehicles.

The mileage estimates for SUVs like Toyota's Highlander Hybrid do not reflect road tests of the vehicles.

Because the EPA's primary concern is emissions, its fuel-economy estimates are secondary. All are based on simulated driving. Professional drivers operate tested vehicles in identical patterns under controlled laboratory conditions, with the tires rolling on a dynamometer. The EPA explains that the test simulates road and aerodynamic forces, but the vehicles are never driven on an actual road.

Two tests are conducted — one for city driving and a second for highway operation. The city test simulates an 11-mile urban stop-and-go loop, with an average speed of 20 mph and a short stretch of simulated freeway driving. The trip lasts 31 minutes and has 23 stops, and 18 percent of the time is spent idling. The highway simulation is a 10-mile trip at an average speed of 48 mph, with no stops and little idling.

Fuel-economy estimates are actually calculated from the emissions generated during these tests. Adjustments are made before coming up with final figures, based on studies showing that real drivers achieve 90 percent of the EPA's city estimate and 78 percent of its highway estimate.

Critics charge that in real-world driving, vehicles get far fewer miles per gallon than the simulations suggest. That may be because the test has not changed in the past three decades. Most people use air conditioning today, but that's not accounted for in the simulation. Also, traffic congestion is much greater now than it was in the 1970s. Owners of gasoline/electric hybrid vehicles may also observe lower real-world fuel economy than the EPA's estimates.

The EPA's fuel-economy test may be in for an overhaul, however. Automotive News reported in January that the EPA has proposed new testing procedures designed to narrow the gap between fuel-economy estimates and actual fuel economy observed by drivers. Under the proposal, city estimates would decrease 10 to 20 percent (or more for hybrids) while highway estimates would be lowered by 5 to 15 percent. If the changes are approved, fuel-economy estimates based on the new tests would first appear on 2008 model year vehicles.

How You Drive Affects Fuel Usage
Bad driving habits can lower mileage of a Subaru Baja or any car.

Bad driving habits can lower mileage of a Subaru Baja or any car.

Some people complain that they can't obtain EPA estimates with their vehicles. However, in addition to possible test flaws, a close look at their driving habits may explain why. If you stomp on the gas pedal when starting off from a stoplight, drive at excessive speeds on the highway or run with underinflated tires, your mileage is sure to be considerably lower than the estimate suggests. Running the air conditioner also consumes quite a bit of extra fuel.

Extra weight, like a full load of passengers or cargo, makes engines guzzle more gasoline than if only one or two occupants were inside. Hilly terrain and cold-weather driving also cut into gas mileage.

Detailed information on EPA testing can be found at www.epa.gov and www.fueleconomy.gov. The EPA's Green Vehicle Guide gives air pollution and greenhouse gas scores for many vehicles.

Posted on 2/1/06