Buoyed in great measure by affordable fuel, America in the 1990s turned its automotive appetite to light trucks. The category includes pickups, minivans, and, the models that experienced the fastest-rising popularity of all-sporty-utility vehicles.

In 1980, light-duty trucks accounted for just 12 percent of new vehicle sales. The share was 31 percent by 1990, and reached a high of 54 percent in mid-2004. For SUVs, the share of the U.S. new-vehicle market was just 10 percent in 1994. By 2004, it was 24 percent.

Light-truck sales didn't slip as gas prices rose during 2005, through SUV buyers did begin to switch from thirsty truck-based wagons, such as the Chevrolet Tahoe and Ford Explorer, to lighter-weight and thriftier car-type SUVs, such as the Chevy Equinox and Honda Pilot.

Even after the price shocks following Hurricane Katrina in September 2005, light trucks still were outselling cars, but the lead had shrunk to 51 percent of the market. And sales of large, truck-type SUVs continued to shrink in favor of car-type models.

As a category, light trucks average about 25 percent lower fuel economy than passenger cars. Within light trucks, the miles-per-gallon spectrum starts with full-size pickups and SUVs and the least efficient, followed by truck-type midsize SUVs, with compact and car-based SUVs the most efficient.

Buying with Fuel Economy in Mind

In general, we urge potential SUV buyers to consider their purchase rationally, not emotionally. Sure, SUVs are trendy, and their high ride height and shear size afford a sense of security. But that ride height requires you to climb, not step, in and out. And tall-riding vehicles are more prone to rollover accidents. Minivans offer more usable interior space than any large SUV, and many station wagons afford nearly as much cargo room as a midsize SUV and more than most compacts. The added traction of all-wheel drive is also available in vehicles that are not SUVs.

But if you're committed to an SUV, here's our advice. If you regularly tow a trailer of more than 5,000 pounds, you need the stout truck-type frame and burley V-8 engine that's the bread and butter of the truck-type SUV. And if you frequently travel in severe off-road conditions, the truck-type frame might also serve you well.

But for every other use to which the vast majority of Americans put an SUV, a car-type SUV is the more sensible, and fuel-smart, choice. They ride and handle better, offer a range of 4-cylinder and V-6 powertrains, and most all-wheel drive (AWD) versions do surprisingly well off pavement, too.

Go about picking a fuel-efficient SUV in much the same way you would a frugal car-without expecting as thrifty a result, of course. Consider the choice of available engines and transmissions, and go easy on the weight-adding options.

Nix 4WD if Economy is Your Goal

Four-wheel drive has its good points, but mileage is not ordinarily among them. EPA fuel-economy estimates and Consumer Guide® road test results illustrate the difference. The extra drivetrain components just add too much weight, so even discreet use of four-wheel drive (4WD) carries a big penalty every day, whether it's engaged or not. Not every 4WD vehicle qualifies as an out-and out guzzler; but unless statistics suggest otherwise, assume that you'll pay plenty for the occasional ability to put four drive wheels to the pavement.

If you don't need the off-road traction versatility of true 4WD, all-wheel drive is an attractive alternative. These systems are lighter in weight than 4WD, and actually are more useful on-road because, unlike 4WD, they require no action from the driver to deliver power to all four wheels. Some systems also offer low-range gearing and oth er off-pavement traction aids.

Hybrids and Diesels

Gas/electric hybrid-electric cars and trucks combine the benefits of gasoline engines and electric motors and can be configured to obtain different objectives, such as improved fuel economy, increased power, or additional auxiliary power for electronic devices and power tools. None of the hybrid cars and trucks on sale in the U.S. require plug-in charging. They instead use a combination of the gas engine's power, and systems that "recapture" otherwise-lost energy from the turning wheels, to recharge the motor's batteries.

Hybrids have grabbed headlines out of proportion to their sales numbers. Though nearly 90,000 hybrid vehicles were sold in the U.S. in 2004, that was only about one half of one percent of the total vehicle market. Leading auto industry analysts say hybrids will top out at just 3 percent of the U.S. market by 2010.

Gas/electric hybrids tend to get better fuel economy in city driving than in highway use. But the bigger surprise has been the gap between the astounding EPA fuel-economy estimates and real-world experience.

This gap was borne out by Consumer Guide® in a six-month evaluation of a 2004 Honda Civic Hybrid with automatic transmission. The EPA rated that vehicle at 48 mpg city, 47 mpg highway. Consumer Guide's® automotive editors drove the vehicle 12,000 miles and averaged 38.3 mpg.

That sort of fuel economy can be duplicated by small, gas-only cars and some diesel cars. But only hybrids combine such high mile-per-gallon returns with low exhaust emissions.

Hybrid cars and SUVs tend to cost more than similar gasoline-powered vehicles. But automakers are increasingly pitching them not as merely fuel-saving purchases but as premium-powertrain vehicles that use the extra muscle supplied by the electric motor in tandem with the gas engine to create vehicles that are both faster and more frugal than gas-only counterparts.

Motorists who were "burned" by the last wave of diesel power in the late 1970s and early 1980s probably wouldn't buy one. Everybody's heard about the horrid reality problems of GM's diesel V-8s, in particular, and the inadequacy of most smaller diesels as well.

Only a handful of diesels remained available through the 1980s, but Mercedes-Benz and Volkswagen are leading a resurgence in diesel availability with engines far superior to earlier versions in silence and performance. For economy, the diesel is hard to beat, delivering as much as 25 percent more mileage (on diesel fuel) than a gasoline engine of similar size.

Buying a new car is confusing enough. In the next section, we'll take a look at the considerations you'll want to keep in mind if buying a fuel-efficient car is your goal.