Keep Your Fuel Expenses Lower Than Your Monthly Payment

Between fluctuating gas prices and environmental concerns, fuel economy is always a hot-button issue. And when gas mileage is the topic, it's a safe bet that sport utility vehicles will top the list for discussion — and criticism.

Except for some of the smallest models, SUVs are among the least fuel-efficient vehicles available. For one thing, SUVs are typically heavier than other vehicles, and extra weight consumes more fuel. In addition, their square-shaped front profiles force their way through the air, rather than aerodynamically slicing into it. Only vans and commercial trucks have fewer aerodynamic qualities than a typical car- or truck-based SUV.

Several factors help determine a vehicle's fuel economy, and size is one of the biggest. Buy a full-size SUV and you can expect mediocre gas mileage. Drive home a compact, and you're almost sure to do better in the fuel-economy derby.

Engine size also matters. Four-cylinder SUVs usually get better mileage than those with V-6 power, which in turn beat models with a V-8 engine. But that may not be true of a smaller engine that is overtaxed. If you do a lot of mountain driving, a larger, more powerful engine is almost mandatory.

Manual transmissions generally, though not always, yield better gas-mileage figures than automatics, but many SUVs — especially large ones — aren't offered with manual gearboxes.

Four-wheel-drive SUVs consume more gasoline than two-wheel-drive models, mainly because of the increased weight of four-wheel-drive systems. In snowbelt states, most SUVs are sold with four-wheel drive, which can help immensely on slippery roads. Two-wheel-drive models tend to be more popular in more temperate regions. Some SUVs come only with four-wheel drive or all-wheel drive, so you may not have a choice in the matter.

With a curb weight of well over 5,000 pounds, Land Rover's Range Rover is a substantial SUV, and this is reflected in its 12/16 mpg rating.

At the guzzler end of the scale, if you decide on the Mercedes-Benz G55 AMG, the EPA estimates it will achieve only 12 mpg in the city and 14 mpg on the highway. A Land Rover Range Rover earns only 12/16 mpg. Other full-size SUVs like the related Lexus LX 470 and Toyota Land Cruiser return only slightly better results with 13 mpg city and 17 mpg highway ratings.

Hybrid Powertrains and Diesel Engines: Making SUVs Miserly

As the 2005 model year begins, only one gasoline/electric hybrid SUV is on sale: the Ford Escape Hybrid. Two more are coming soon from Toyota and Lexus: the Highlander Hybrid and RX 400h, respectively.

Because hybrids have been available for only a few years, little data exists on reliability. Anecdotal evidence from manufacturers, however, indicates that few significant problems have occurred on hybrid vehicles that have been on the road for a while. Battery packs need to be replaced eventually, but they're warranted for a lengthy period and could last as long as the vehicle itself.

For 2005, the Jeep Liberty may be equipped with a 2.8-liter four-cylinder diesel engine that generates 160 hp and 295 pounds-feet of torque.

Diesel engines were something new for U.S. SUVs in the 2004 model year when Volkswagen introduced a variant of its Touareg with a mighty V-10 diesel engine. For 2005, Jeep edges into the fray with its diesel-powered Liberty. Don't expect frugal mileage from the Touareg, but the Jeep Liberty should earn a respectable EPA rating. Diesel engines have been around far longer than hybrid powertrains and are best known for their strong low-end torque output, which is beneficial for acceleration, towing and hill-climbing.

Another factor to consider is whether or not the SUV you're looking at requires premium fuel, especially when buying a large, upscale model. Paying an extra 20 cents or more per gallon adds up over the course of a year. Many automakers hedge their bets, stating that premium gasoline isn't required but is recommended for improved performance. Some models, however, require premium-grade gasoline.