Even if you've established your primary needs for a sport utility — carpooling, cargo carrying, long-distance traveling, off-roading — determining the degree of those needs can heavily influence your purchase. For instance, say you want a spacious SUV that doesn't look bulky like a full-size truck — then cross the Chevrolet Suburban, Cadillac Escalade and Nissan Armada off your list. The Subaru B9 Tribeca, Nissan Murano and Infiniti FX35 are sleek-looking SUVs.

The Land Rover LR3's clever asymmetrical rear hatch allows from one side a farther reach inside the vehicle to stow goods. + enlarge image  |  view gallery >

If you need seating for six or seven passengers, but know that the rearmost chairs will only be occupied when carpooling, then a Cadillac SRX (with 24.2 inches of third-row legroom) might be a good choice. However, if larger passengers will be squeezing into the rearmost seats, the SRX's might be too cramped. Make sure and try out the third-row seating on every SUV you're considering, especially if you expect anyone larger than a middle-schooler to fit back there. Mercedes-Benz's R-Class and Land Rover's LR3 both have generous third rows, offering 32.4 inches and 36.3 inches of legroom respectively.

If you have a long work commute or run a lot of errands around town, a compact or midsize model can provide a blend of efficiency and capability. Look for convenient options, such as a rear hatch that allows either the entire unit or just the glass to be opened (Mercury Mountaineer), an automatically closing rear hatch (Lexus RX 330) or other clever engineering, such as the Land Rover LR3's asymmetrical clamshell design on its rear hatch.

If you need to pull a boat, camper or horse trailer, then towing capacity (how much a vehicle can safely pull) is crucial. If you try and tow more than your SUV is able, you risk damaging the vehicle and, in the worst-case scenario, endanger occupants with the potential of getting into an accident as the brakes, suspension and other systems may not hold up.

The construct of the vehicle — whether built like a car or like a truck — plays a big roll here. Read more about this in the Car-Based or Truck-Based section.

The heavier the load, the more power and size is required to tow or haul it. A compact SUV with a six-cylinder engine, like the BMW X3 (3,500 pound towing capacity), might struggle to pull a 22-foot boat. The midsize BMW X5 with its potent V8 engine can tow nearly twice as much (6,000 pounds), but still might not be able to handle a camper.