SUV Buyer's Guide

Off-Road Considerations

by SUE MEAD AND MATTHEW DE PAULA, ForbesAutos.com

Driving skill not withstanding, off-road capability is largely a product of four-wheel-drive systems, suspension hardware, tire choice and gearing. The dimensions of a vehicle also figure prominently in its ability to navigate rough landscape.

There are few constants, however, as specific situations demand different specifications. For example, uneven terrain is often easier to conquer with a vehicle that has a shorter wheelbase, such as the Land Rover Freelander, because a lot of space between the wheels can cause the vehicle to scrape bottom and get stuck going over humps and boulders. However, short front and rear overhangs are essential to clearing tall obstacles and ascending or descending steep grades.

2006 Hummer H3
The width of a vehicle is complicated as regards off-roading. Wide vehicles tend to be more stable, but might not fit on narrow trails. For all its rock-climbing prowess, the girth of Hummer's H1 Alpha (7 feet, 2.5 inches wide, without the mirrors) is a serious liability on the woodland tracks of New England. Smaller SUVs, like the Land Rover Freelander can fit between trees and on narrow paths where bulkier vehicles can't pass.

Other variables that dictate off-road ability include ground clearance, the type of four-wheel-drive system and engine output. More height above the terrain (ground clearance) allows for easier maneuvering, assuming the vehicle isn't so top-heavy that it's prone to tipping over.

Car-based SUVs tend to have less ground clearance than truck-based SUVs. And generally speaking, larger SUVs tend to have better ground clearance than smaller SUVs. So if you envision doing serious stints off road, then it might be a good idea to cross most compact SUVs off your list. However, the Land Rover Freelander and a couple of Jeeps we don't cover (Wrangler and Liberty) can hold their own on tough terrain.

Volkswagen Touareg
Full-time four-wheel drive with a low-gear setting is necessary to power over the roughest terrain. The low gearing allows the SUV to comfortably travel at a snail's pace, which is the rate for most off-roading. An engine with a lot of torque is also essential because torque dictates the power of an engine at lower speeds and you'll rarely be revving the engine hard when crawling along off-road trails.

Many SUVs that are designed for serious off-road use, including all Land Rovers, some Jeeps, the Volkswagen Touareg and others, have an arsenal of electronic gadgets that make traversing rough terrain much easier than in the past. One example is called "hill decent control", where the SUV's on-board computer manipulates the brakes, throttle and transmission to set the ideal rate of decent. A similar function helps SUVs ascend steep, slippery grades without losing traction.

These high-tech automated features make it easier for the average driver to conquer rough terrain over which only a seasoned off-road expert would've dared to venture in the past. That said, off-roading carries many risks and can quickly turn into a perilous nightmare without proper preparation, training and forethought.

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