Sport Utility Vehicles have avoided the stricter mileage standards placed on passenger cars because they were originally built on truck frames. But concern over fuel economy and the advent of hybrid cars are gradually increasing fuel economy for SUVs, although the larger versions are still gas guzzlers compared to small economy cars.
The Environmental Protection Agency changed mileage standards for all vehicles for the 2008 year, taking into account previously ignored factors such as acceleration, cold weather, higher speeds and air-conditioner use. The change lowered the mileage estimates for many SUVs, from 6 to 16 percent in some cases. The Ford Expedition, for instance, dropped from 14 miles per gallon in the city to 12 mpg between 2007 and 2008, and from 20 mpg to 18 mpg on the highway.
Automakers recognizes three general categories of SUVs: small, mid-sized and large. The GMC Yukon and Chevrolet Tahoe are considered large, the Ford Explorer and Jeep Grand Cherokee mid-sized, and the Hyundai Tucson and Mercury Mariner V6 are considered small SUVs.
The most fuel-efficient small SUVs were four-cylinder cars, with the top three all hybrids. The Ford Escape hybrid, the Mazda Tribute hybrid and the Mercury Mariner hybrid each came in at 34 mpg in the city and 31 mpg on the highway. Hybrids often have better city ratings because increased use of brakes helps power the vehicle.
The two non-hybrids with best fuel economy were Jeeps with manual transmissions--the Compass and the Patriot, both with ratings of 23 mpg in the city and 29 on the highway.
The two worst small SUVs in terms of mileage were also Jeeps--the Wrangler with an average of 15 mpg city/highway and the Liberty with an average of 16 mpg.
For mid-sized SUV, hybrids once again had the highest fuel economy as measured by the federal Department of Energy and the Environmental Protection Agency. The Lexus RX hybrid and the Toyota Highlander hybrid both came in with an average 26 mpg city/highway rating.
The worst mid-sized SUVs were the Jeep Commander 8 cylinder, and the Landrover LR3, each with an average of only 13 mpg, a rating that matches the worst large SUVs.
The hybrids also led the pack with large SUVs in the category of fuel efficiency. The Chevrolet Tahoe hybrid and the GMC Yukon hybrid both had an average city/highway rating of 21 mpg.
Unsurprisingly, the large SUVs led the bottom of the category in terms of poor mileage. The Cadillac Escalade, Chrysler Aspen, Dodge Durango, Ford Expedition and Nissan Armada each had an average 13 mpg city/highway fuel economy rating.
