Even though most drivers would shudder at the thought, some of the priciest, most luxurious SUVs relish trouncing through mud, bounding over boulders and powering up steep inclines. Think of them as well-mannered brutes, frustrated for lack of opportunity to display their brawn.

As car buyers abandon truck-based SUVs for car-based ones — called “crossovers” by industry insiders — to gain more on-road comfort and capability, it’s the costlier truck-like models that continue to flaunt true rock-crawling abilities. (Click here to read about the difference between car- and truck-based SUVs.)

“This is the carryover from the idea that any ‘real’ SUV had to be able to get to the top of the mountain with its 4×4 system,” says George Peterson, president of AutoPacific Group, a California-based automotive research firm. In many ways, this makes a luxury SUV the vehicular equivalent of costly professional-quality stove and oven ranges sold to wealthy people who don’t cook much but would like to think they have the tools to whip up a gourmet meal if the need ever arises.

“Substantially less than 10 percent [of luxury SUV owners] indicate that they actually go off-roading,” says AutoPacific’s Peterson. “We actually think that the percentage that actually off-roads is less than 5 percent, but we have to go with what the owners report.”

While some lower-cost SUVs like the Jeep Wrangler and Nissan Xterra boast the largest percentage of “real” off-roader enthusiasts — Jeep says 60 to 80 percent of Wrangler owners take their vehicles to the trails — some large luxury models are equipped to tackle tough terrain. “The price of a Land Rover has always been higher than many other four-wheel-drive vehicles, based not just on luxury but on capability,” says Bob Burns, off-road events manager for Land Rover North America. “Range Rover customers want to buy the best and want to experience what their vehicles are built to do.” Go to the Land Rover Showroom to compare prices for different models.

Land Rovers have the highest off-road penetration among luxury SUVs, with 26 percent of all LR3 owners engaging in “real” off-roading, and 22.2 percent of all Range Rovers and 14.8 percent of Range Rover Sport drivers occasionally leaving the pavement. By contrast, the study found that no Cadillac Escalade EXT, Infiniti QX56 and Volvo XC90 owners ever venture off-road. (See the chart below for more data.)

Defining ‘Off-Road’

How motorists define off-road driving affects those numbers. “Off-road for some of these folks could be in the shopping mall parking lot,” Peterson says. “We try to get at that by differentiating ‘real off-roading’ with ‘getting to fish/camp/hike sites’ in our study.” In other words, AutoPacific defines “real” off-roading as driving on rugged off-road trails, versus merely traversing a dirt or gravel path to access a fishing, hiking or camping site, for instance.

“The definition of ‘off-road use’ varies greatly, and we’re OK with that,” says Land Rover’s Burns. “Some customers consider it to be the snowy driveway to the ski house, while others may well define it as scaling the Sierra Nevada mountain range.”

Industry analysts agree that among all luxury SUV brands, Land Rover does the best job of creating an active community of off-roaders. For starters, most dealerships maintain their own off-road test courses, which can range from a simple hill climb to a full-blown facility for buyers to test their vehicles’ mettle and their own fear threshold. Beyond that, Land Rover dealers help make sure their customers have access to an assortment of off-road events and excursions.

“Our owners have the option of learning how to drive their vehicles off-road at a driving school, a retailer-organized event, or they can take a dive off the deep end by signing up to attend a Land Rover Adventure,” Burns says.

SUVs have been around for decades, arguably starting with limited but growing enthusiasm for truck-based station wagons post-WWII that were generically called “Suburbans” (long before Chevrolet trademarked the name. Luxury SUVs are a more-recent phenomenon. Born out of the SUV boom in the 1990s, today every mainstream luxury brand except for Jaguar offers at least one SUV.

Kings of Off-Road

Vehicle	Percent of owners who drive off-road
BMW X3	1.4%
BMW X5	7.4%
Cadillac Escalade	4.3%
Cadillac Escalade EXT	2.2%
GMC Yukon XL	0.0%
Infiniti FX	6.1%
Infiniti QX56	2.2%
Land Rover LR3	0.0%
Land Rover Range Rover	26.0%
Land Rover RR Sport	22.2%
Lexus GX 470	14.8%
Lincoln Navigator	6.1%
Mercedes M-Class	9.1%
Porsche Cayenne	3.1%
Subaru B9 Tribeca	10.5%
Volkswagen Touareg	3.5%
Volvo XC90	9.8%
Average Luxury SUV	7.15%

What to Look for

There are some basic parameters that every SUV must have for serious off-road duty. Primary among them is a four-wheel-drive system with low-range gearing that enables a slow crawl often needed to negotiate rough terrain.

Other important specifications include ground clearance, approach and departure angles, and fording depth. Go to the next page for definitions of these terms. A host of expensive accessories are available to improve off-road performance and safety. But instead of focusing on expensive add-ons, like brush guards and winches, those serious about off-roading should invest in training, off-roading expert Pietschmann says.

“The main thing you want to have when you’re off-roading is a prepared driver,” he says. “Ninety percent of everything off-road has to do with the driver — only 10 percent depends on the equipment.”

Bill Burke, an off-road driving instructor who runs 4-Wheeling America, in Fruita, Calif., stresses that drivers should adhere to the “three Ps” of off-roading:

Patience – Drive slowly enough to be able to gauge the terrain and react accordingly.

• Planning – Stop and decide exactly how to negotiate an obstacle rather than just plow forward without a plan.

• Practice – Learn the capabilities of your vehicle and its equipment in safe surroundings before setting out to conquer a remote trail.

It’s also imperative to always be mindful of how the vehicle will impact the environment, Burke says. “Treat the outdoors where you drive like your own home — take care not to damage it or clutter it.” Land Rover’s motto of “tread lightly” encapsulates this idea.

Prior to the SUV boom of the 1990s, most SUVs were referred to as “four-by-fours,” expressed as “4x4s,” by virtue of four-wheel-drive systems that imbued them with nearly superhuman off-road and foul-weather abilities. Back then you had to get out of the truck and manually “lock” the front wheel hubs to send power to all four corners, however. Today’s 4×4 systems are much more sophisticated and come in several varieties, each of which is skewed more toward either off- or on-road use.

Here’s a quick rundown of the various similarities and differences between the competing types of systems:

• Part-Time 4WD: Typically the most-basic type of 4WD system found on the least-expensive models; the engine powers only the rear axle until the driver pushes a button or shifts a lever to engage the front wheels. Vehicles with this system include the Jeep Wrangler and Nissan XTerra.

• Full-Time 4WD: A driver can choose between rear-drive, 4WD and an “automatic” mode that engages the front wheels as needed when sensors detect wheel slippage. This system typically affords the best compromise between on- and off-road use. Vehicles with this system include the Chevrolet Tahoe and Ford Expedition.

• Permanent 4WD: Found on many higher-priced SUVs, this includes the automatic system mentioned above, but doesn’t offer two-wheel-drive. To some degree, all four wheels receive power at all times. Such systems may or may not include low-range gearing for extreme off-roading. Vehicles with this system include the Hummer H2 and Land Rover Range Rover.

• All-Wheel Drive: Similar to permanent 4WD and available on most car-based “crossover” SUVs and a few truck-based SUVs. AWD not only boosts traction, but also can improve cornering abilities on-road. Some systems vary the amount of power sent to each wheel, individually. Unlike 4WD, however, no low-range gearing is included, which means the system is not intended for serious off-roading. Vehicles with this system include the Buick Enclave, Cadillac Escalade, Lexus RX 350 and Mercury Mountaineer.

Some automakers will refer to their car-based SUVs as having 4WD, when really they’re equipped with AWD. This is a marketing ploy to create a burly image. The rule of thumb is that if it doesn’t include a switch or lever to engage low gear, it’s not a true 4WD system.

About Our Ranking

In our top 10 list of luxury off-road SUVs, we’ve listed the models retailing for $30,000 or more that we feel are the most rugged, based on a combination of personal experience, published performance reports and the manufacturer’s specifications.

We’ve included a few critical specs in that regard for each model on the list: ground clearance, approach and departure angles, and fording depth (see below for definitions of each). Sometimes these numbers are expressed as a range because the measurements either differ from version to version within a particular model line — given different suspension systems, tires and so on — or vary because of features like an adjustable-height suspension. We’ve also included a list of off-road enhancements available as factory options for each ranked model, though separate dealer-installed accessories may also or alternately be offered.

Definitions

• Ground clearance: One of the key specs for those looking to take an SUV off-road, ground clearance refers to the space between the lowest point on a vehicle’s chassis and the ground beneath it. The higher the ground clearance, the less likely the underbody and associated components will sustain damage over rocky and uneven terrain. Generally, this is measured from a point under the differential housing, though on some models this may not actually be the lowest spot, so bring a tape measure with you if you’re serious about comparing various models’ ground clearances. A serious down side to having higher ground clearance is the resulting higher center of gravity, which adversely affects the vehicle’s on-road handling and makes it more susceptible to rollovers. Many luxury SUVs offer suspensions that can be lowered for highway use and raised for added off-road clearance at the push of a button.

• Approach angle refers to the steepest incline angle a vehicle can drive up from a flat surface without damaging the front bumper or undercarriage.

• Departure angle is like the approach angle for the back of the vehicle. It refers to the degree of incline a vehicle can negotiate without having the rear bumper or other overhang scrape.

• Fording depth represents the maximum depth at which an off-road vehicle can operate in water. Fording depth is important if you plan to cross creeks and streams along a trail.

10. Volkswagen Touareg
The Touareg hasn’t been a big seller, despite being both luxurious and capable. It shares some components with the Porsche Cayenne. A standard 4Motion permanent AWD system enables the Touareg to scale a 45-degree grade; a sophisticated suspension gives relatively responsive on-road handling. Three engine choices include a 310-hp 5.0-liter V10 turbodiesel that generates 553 pound-feet of torque for extreme pulling and climbing power. A freshening later this year will rechristen it the Touareg 2.

9. Lexus GX 470
Introduced as a smaller and lower-cost alternative to the LX 470, the GX 470 is essentially a luxury version of the Toyota 4Runner with a V8 engine. A full-time 4WD system is standard, the vehicle’s ActiveTRAC technology is able to apply the brakes to a slipping wheel while transferring the engine’s power to wheels with better traction. An optional Kinetic Dynamic Suspension System hydraulically controls a set of oversized front and rear stabilizer bars to further enhance its trail response.

Off-Road Options:
Kinetic Dynamic Suspension System ($1,750)

8. Porsche Cayenne
After taking the 2007 model year off, the Porsche Cayenne is updated and reintroduced as an early-2008 entry. As before, it’s offered in 290-hp base, 385-hp S and 500-hp Turbo S models, the latter of which boasts the best off-road specs, but is priced just short of $100,000. The Cayenne’s sophisticated 4WD system can send up to 100 percent of the vehicle’s traction to the front or rear axle if needed. The available Porsche Dynamic Chassis Control (PDCC) system limits vehicle roll on pavement through corners and enables maximum axle articulation and improved traction off-road.

Off-Road Options:
Fire Extinguisher ($140); Off-Road Technology Package ($2,640; includes rear differential lock, rocker panel protection, additional skid plates and undercarriage protection); Porsche Dynamic Chassis Control ($3,510); Sportdesign Package with Off-Road ($3,395; includes front and rear lower bumper covers, extended roof spoiler and rocker panel extensions, front and rear stabilizer bars that can be disconnected hydraulically, rear differential lock, additional skid plates and undercarriage protection, headlamp washers, additional tow lug)

7. Mercedes-Benz G500
Derived from a German military vehicle designed in the 1970s, the G500 soldiers on as an unabashedly boxy, low-volume, high-priced and somewhat eccentric luxury SUV. While it offers a comfortable cabin, the G500 remains rugged and is one of the few SUVs of any kind to offer three separate locking differentials for exceptional off-road aptitude. Its 292-hp V8 engine has to work hard to move the un-aerodynamic bulk with authority; the G55 AMG version includes a much-quicker 469-hp supercharged V8, but at a steep price.

Off-Road Options:
N/A

6. Lexus LX 470
Lexus’ upscale version of the venerable Toyota Land Cruiser excels as a posh off-road adventurer, thanks to a hardy, full-time 4WD system that features a locking center differential and four-wheel traction control. A height-adjustable adaptive suspension provides added ground clearance for off-road use. While the 2007 model’s 4.7-liter V8 is rather meek at 268 hp, the vehicle will receive a more-powerful 381-hp 5.7-liter V8 engine with its 2008 redesign, which will prompt a name change to the LX 570.

Off-Road Options:
N/A

5. Land Rover Range Rover Sport
This big SUV is sporty by SUV standards, thanks largely to well-balanced handling and strong engines (300-hp V8 or 390-hp supercharged V8). However, the Range Rover Sport can be just as entertaining on the trails. It shares the LR3 and Range Rover’s low-range 4×4 gearing, lockable center differential and the Terrain Response system that maximizes performance according to five settings that correspond to different road conditions; three of which are off-road (mud, sand and rocky surfaces).

Off-Road Options:
Locking Rear Differential ($500); Dynamic Response Package ($2,000; includes dynamic-response suspension, Brembo front brakes)

4. Land Rover LR3
You could certainly pay less for a midsize SUV, but few combine the inherent luxury and off-road readiness of the LR3. Known as the Discovery in other markets, this upper-crust Brit offers a choice of V6 and V8 engines, with five- or seven-passenger seating. A center-locking differential, a long list of chassis control functions and the automaker’s adjustable Terrain Response system combine to deliver secure handling and a smooth ride in a wide range of conditions.

Off-Road Options:
Heavy-Duty Package ($625; includes active locking rear differential, full-size spare with alloy wheel)

3. Mercedes-Benz GL450
Introduced for 2007, the seven-passenger GL450 is well suited for both carpooling and off-roading. Unlike most 4x4s, it’s built on a reinforced unibody structure that affords more of a car-like feel on pavement than the truck-based competition. Be aware, however, that you’ll need to specify the $2,200 Off-Road Package to maximize ground clearance and off-road prowess. A 4.6-liter V8 engine is rated at a hearty 335 hp and comes mated to a seven-speed automatic transmission.

Off-Road Options:
Off-Road Package ($2,200; includes additional ground clearance, locking differentials, underbody skid plates, adaptive damping suspension)

2. Land Rover Range Rover
With a well-heeled British pedigree, the V8-powered Range Rover continues to lead SUVs that venture into the wilderness. It’s also one of the costliest, most luxurious SUVs offered. Land Rover’s Terrain Response system allows the driver to tailor the vehicle’s electronic controls and traction aids according to various road conditions, while an electronic rear differential (standard on the 400-hp Supercharged model and optional on the 305-hp base version) improves the vehicle’s already tenacious trail-forging talents.

Off-Road Options:
Locking Rear Differential ($500)

1. Hummer H2
Though it has become the mascot for excessive consumption, the Hummer H2 is nonetheless one of the most capable off-road vehicles around. A rugged, full-time 4WD system with low-range gearing enables it to climb 16-inch steps and rocks; short front and rear overhangs and a generous ground clearance mean there’s less of a chance the vehicle will get hung up on bumpy trails. A 325-hp 6.0-liter V8 offers ample power and a 7,000-pound tow rating.

Off-Road Options:
Adventure Kit ($325; includes two-way radios, tire deflators, light, binoculars, compass, wind-resistant lighter); Adventure Series ($2,530; includes brush guard, first-aid kit, roof rack, CD changer, air suspension, tool kit, floor mats); Brush Guard (basic, $525; wrap-around version, $675; chrome wrap-around version, $995); Off-Road Lights ($1,410); Spot Lamps ($450; roof mounted, $998); Taillamp Protectors ($250; chrome, $350)
(C)Jim Gorzelany, Forbes