Sport-utility vehicles (SUVs) are generally classified into three groups — compact, midsize and full-size — though the range of vehicles within each group varies widely. You will often hear the term "crossover" used, but this is really just a marketing term to describe a utility vehicle based on a car platform rather than one based on a truck platform. As you move up in size you also move up in engine power, towing ability, passenger room and price. There are luxury models in each of the groups.
Car-based SUVs (typically known as crossovers) generally provide attributes associated with cars, like sharper handling, better fuel economy, a quieter, more comfortable ride and more interior room. Truck-based sport-utility vehicles are sturdier but heavier, can tow more weight and generally provide better off-road mobility.
Compact SUVs are the most affordable, and prices for base models start at less than $20,000. Midsize and full-size SUVs vary greatly, with base models starting in the mid-$20Ks and going all the way up to the mid-$40Ks. Luxury SUVs start around $32,000 and can top out at more than $100,000.
Compact SUVs offer both four- and six-cylinder engines. Midsize sport-utes typically come standard with six-cylinder engines, but can be had with four- and eight-cylinder power plants as well. Full-size SUVs feature V8 engines. The most economical four-cylinder compact SUVs can achieve combined mileage figures in the low-to-mid 20s, while most six-cylinder sport-utes average in the upper teens (though the handful of gas-electric hybrid models do much better than that). Full-size vehicles generally get between 12 and 20 mpg.
Check the availability of features like antilock brakes, front-seat side airbags, full-length side curtain airbags and stability control. Features like rearview cameras, parking sensors and knee airbags are becoming increasingly available on non-luxury SUVs, while premium brands are utilizing high-tech electronics to warn drivers of blind-spot intrusion and impending collisions. Even so, keep in mind that SUVs are often both large and heavy, so they are not as agile or maneuverable as a car. Be aware of crash test scores, but note that the National Highway Traffic Safety Administration has recently adopted more strenuous testing procedures, so the ratings of recently tested models aren't directly comparable with those tested in the past.
Luxuries like automatic climate control, heated seats, iPod interfaces, navigation systems, keyless start systems and Bluetooth capability can often be found in all utility vehicles. Regardless of vehicle size, keep an eye open for family-friendly features like rear-seat entertainment systems, flat-folding third-row seats, special storage bins and rear seats that slide and/or recline.
All but a few SUVs are designed to carry at least five passengers. Most compacts provide enough rear legroom for full-size adults, with several offering fore-aft seat adjustments to extend either passenger space or cargo capacity. The same goes for larger SUVs, but these wider vehicles are more likely to accommodate three-across seating. Most larger SUVs and even some midsize ones offer the option of adding a third-row seat for additional passenger capacity. Such seats are generally best suited for kids, but a few full-size SUVs have third-row seats that can comfortably fit adults.
Every sport-utility allows you to fold or remove the rear seats for more cargo capacity. When the rear seat is folded, compact sport-utes can provide as much as 70 cubic feet of capacity, while midsize SUVs can expand to as much as 100 cubic feet. Full-size SUVs offer cargo areas in excess of 100 cubic feet.
Two-wheel drive (2WD) means that only the front or rear wheels provide power to the vehicle. Four-wheel-drive vehicles allow the driver to select either two- or four-wheel drive, and the four-wheel-drive (4WD) system sometimes features dual-range gearing for even more traction and mobility while off-roading. All-wheel-drive (AWD) vehicles automatically distribute power in varying degrees to the wheels with the most traction, and they are typically best suited to all-weather driving rather than pure off-roading. All-wheel drive generally weighs far less than a 4WD system, but there is generally an impact on fuel efficiency even so. Part-time 4WD and AWD systems attempt to minimize fuel-efficiency compromises by permitting two-wheel drive.
Since compact SUVs are generally smaller, lighter and have less complex four-wheel-drive systems, maintenance and fuel costs are generally lower. With larger size and larger engines, midsize and full-size sport-utes by and large get worse mileage and are more expensive to insure. This is especially true of truck-based models.