The 4x4 Equation
What Makes Four-Wheel and All-Wheel Drive Vehicles So Popular?
From the Print Edition:
Linda Evangelista, Autumn 95
Drive into any suburban mall parking lot today and take a look around. Instead of row after row of sleek sedans with virtually the same sloping roof lines, there are bulbous tops sticking up everywhere. The protrusions range from tall and square to steroidal bulging at the sides. But the impression is the same: Something new and unusual has taken over the mind-set of American drivers.
The answer is simple. Sport utility vehicles--trucks that look like a Volvo station wagon squeezed in a vice--are the fastest-growing segment of the car market today. For many upscale buyers, especially suburban pioneer types, these quasi-trucks are competing with Jaguar, Lexus and Infinity for their automotive dollar.
No longer outback transportation with a harsh bouncing ride, four-wheel drive (4WD) sport utility vehicles (SUVs) have evolved far beyond their military, off-the-road roots, becoming mobile status symbols and anti-aging antidotes for graying baby boomers. A million and a half units are sold in the United States each year, many with every option and accessory available on the most deluxe of import sedans.
Yet few purchasers understand what they are getting, and manufacturers have done little to educate the public as to the nature, differences and relative advantages of their designs. Most new buyers don't understand how 4WD works, nor do they realize that they now legally own a light truck, not even a car.
SUVs derived from Willys-Overland's military jeep, developed in 1940 for U.S. Army use in the Second World War. After the war, consumer demand for a civilian jeep was minimal. Utilitarian and cumbersome, with amenities such as windshield wipers considered lavish, the spartan jeep lacked mass appeal. A few were used for recreational off-roading or by the U.S. Park Service. International Harvester and Land Rover developed 4WD vehicles suitable for agricultural use, while Toyota came up with models designed for police and forestry use in Japan. But overall, SUV sales languished for decades. As recently as 1982, SUVs accounted for less than 2 percent of total vehicle sales in the United States.
But in the early 1990s, something happened. Chrysler introduced its upscale Jeep Grand Cherokee, the first four-door SUV, while Ford presented its Explorer--sleek, stylish cousins to the workhorses of earlier decades. Sales jumped to more than 5 percent in one year. Today, one in every 10 new vehicles sold in the United States is an SUV.
Why have SUVs become so popular? From the consumer's perspective, some of the success is due to a larger trend--America has become a nation of truck drivers. Forty percent of new vehicle sales in the United States are light trucks, which include minivans, pickups and SUVs. Now SUVs are the chic practical alternative to mundane minivans or stodgy station wagons for domesticated chores, turning erstwhile domesticated housewives into urban road warriors. Being in such demand, they carry a prestige beyond their price tag, so they make comparatively inexpensive substitutes for luxury cars. In a crowded society with more and more limits, SUVs have broad appeal, from Yuppies turning 50 to hip Generation Xers. The image is about youth, rugged individuality and time for outdoor activities like hunting, fishing or skiing. It is the "I can do anything," conquering the wilderness, crossing obstacles feeling. And these powerful images sell.
SUVs are a manufacturer's dream, a profit bonanza, and their last great wild growth frontier. The government-mandated fuel economy manufacturers must achieve is substantially lower for light trucks (20 mpg versus 27 mpg for cars). And the U.S. Treasury doesn't collect a 10 percent luxury tax on trucks as it does on cars selling for over $32,000. Best of all, it is the largest single automobile market where foreign manufacturers are comparatively weak.
Without SUV sales, most manufacturers' profits would be substantially lower. Sport utility vehicles have a median purchase price $3,000 higher than cars, and manufacturers are literally selling all they can make. With that kind of demand, they don't need to overspend on marketing promotions or dealer incentives. The 10 percent of the vehicle market that SUVs occupy contribute a whopping 40 percent of industry earnings!
Compared to cars, SUVs and other light trucks are relatively unregulated. Most of the safety equipment that is mandatory in cars is not yet required for trucks. But SUV safety is a complicated issue. Eighty percent of SUVs have 4WD for better traction: People can drive them in snow, ice, mud and sand where ordinary passenger cars would become stranded. They have higher ground clearance and seating than cars, giving drivers increased visibility. But this elevation also raises the center of gravity, making SUVs more top-heavy and harder to handle around turns and in crosswinds, and therefore, more susceptible to rollover. SUVs have a rollover fatality rate two to three times that of cars.
Although SUVs, with their rigid, heavy truck bodies, are perceived to be more crashworthy than cars, in some accidents they are more dangerous. Unlike passenger cars, SUVs are not usually designed with energy-absorbing crumple zones. As a result, a Volvo 940 protects a driver from fatal injuries in a frontal crash four times better than, for example, a Land Rover Discovery or a Mitsubishi Montero.
Actually, the biggest danger in driving an SUV is false confidence. Many SUV accidents are caused by a driver's inability to stop suddenly--better traction doesn't mean better stopping. No matter how expensive and sophisticated the vehicle, control, traction, steering and stopping ultimately depend on four little patches of tire, where the rubber meets the road.
Four-wheel drive divides the engine's power among all four wheels instead of two, the result being superior lateral stability and handling. After all, no vehicle today uses only two wheels to brake, and some sophisticated sports cars even steer with all four wheels. But 4WD systems differ greatly in performance, function and sophistication.
The heart of any 4WD system is a gearbox next to the transmission called a transfer case. It divides the engine torque and sends it to the front and rear axles. Most 4WDs also have a separate set of low gears for engine breaking, hauling a trailer or crawling over rough terrain. What sets apart 4WD systems are the number and type of grapefruit-sized gear arrangements called differentials. A 2WD vehicle only has a single differential, while part-time 4WDs have two, and full-time 4WD or AWD vehicles have three. When a car goes through a turn, each wheel is turning at a different speed. Differentials allow each wheel to be driven at a different speed.
Part-time 4WD is the least expensive, most common and least convenient type of 4WD. The Isuzu Rodeo, Suzuki Samurai and SUVs with similar part-time systems require that a driver come to a complete stop before shifting between 2WD and 4WD. The transfer cases of some part-time 4WD systems--such as those standard in the Rodeo and the Jeep Wrangler, Cherokee, Grand Cherokee Laredo and SE--lock the front and rear driveshafts together when entering 4WD. SUVs in part-time 4WD mode should not be driven on dry or damp hard-surfaced roads, because it forces all four wheels to rotate at fixed speeds, causing the tires to skip. They also require driving slowly in strong crosswinds and around curves.
Higher in cost and convenience are the various "shift-on-the-fly" part-time systems standard in the Ford Bronco, the Nissan Pathfinder and the Toyota 4Runner. With shift-on-the-fly, the transfer case allows shifting in and out of 4WD mode while the vehicle is in gear. Depending on the model, mode shifting is possible at speeds as fast as 55 mph.
Part-time and shift-on-the-fly systems have either manual or automatically locking front wheel hubs that must engage the front axle for a driver to shift into 4WD mode. When returning to 2WD, a driver must either stop, for manual-locking hubs, and get out of the SUV to twist the lock on the hubs back to the "free" position, or he must back the vehicle up as much as 15 feet to disengage automatic-locking hubs. Were this unlocking not done, driving in 2WD mode would result in unnecessary and damaging driveline wear and much lower fuel economy.
The most functional and expensive type of 4WD is full-time 4WD. The A.M. General Hummer, all Land Rover models, the Toyota Land Cruiser, the Mitsubishi Montero, the 1995 Ford Explorer and the Chrysler Jeep Grand Cherokee Limited are equipped with full-time, all-surface 4WD. These models require special preparation to be towed and must only be transported on a flatbed tow truck.
Full-time systems are either permanent or set-and-forget type 4WD systems. Their transfer cases have either a "limited slip" differential or an "open" differential and a "viscous coupling" that variably distributes torque to the front and rear axles as needed, while allowing the axles to turn at different rates. Set-and-forget 4WD systems also have an automatic front axle system that eliminates the need for locking front wheel hubs.
All-wheel drive (AWD) is a form of permanent, full-time 4WD without a low gear range. Manufacturers have chosen not to publicize AWD or educate the public about its value; instead, they focus attention on their more profitable, but less effective, traction control systems. As a result, even though AWD improves handling on wet or dry roads, it sells primarily in northern snow states. When Ford recently started to advertise the AWD option for its Aerostar minivan in the Canadian market, orders jumped by a factor of four.
AWD is available on the Chevy Blazer and the Oldsmobile Bravada. But best of all, AWD is available on vehicles other than SUVs. Most minivans have an AWD option, which improves overall handling, towing and bad weather driving. Subaru has a complete line of reliable subcompact and compact sedans, station wagons and a sports car available with AWD. Audi also has AWD as an option on all its cars, including a sedan, sports sedan and station wagon. In Europe, Mercedes offers AWD, which it calls 4Matic, on sedans and station wagons, while BMW offers its 525ix with AWD. Its 325ix sedan, which was available briefly in the United States, is now the most difficult to find of secondhand BMWs.
Although 4WD is now synonymous with high-off-the-ground sport utility vehicles, where it truly shines is in the virtually unknown category of AWD sports cars. Sports cars routinely have high-performance engines that generate lots of torque, in addition to wide, low-aspect-ratio speed-rated tires, low centers of gravity and ground clearances, and tight steering and suspension geometries. Properly controlling a good sports car takes education and experience.
Sports cars are sensitive to changes in weight distribution during acceleration and braking. Depending on engine location, they will understeer (with front-wheel drive) or oversteer (with rear-wheel drive) through turns. And sports cars generate enough horses to overpower and spin the wheels. Anyone buying a Corvette or the like should attend a three-day specialized driving course at racing schools such as those run by Skip Barber, Bob Bondurant or Jim Russell to develop the necessary handling skills.
A trained racing driver will be able to take advantage of a car's handling, but novices can find pushing the limits of a sports car to be dangerous. AWD's true value is improving high-performance car handling for anyone who is less than a seasoned professional. By distributing the engine's power over all four wheels, many sports car idiosyncrasies go away. Tires are near impossible to burn. Steering is precise and forgiving. Road holding is measured and noticeably improved. Many people experience an identical reaction when first driving a 4WD sports car: "It feels like its riding on rails!"
Some track racing drivers initially carped at adding the extra 100 or so pounds of AWD to their cars. Because they can't oversteer and slide into curves, they found AWD to be a bit slower through fast turns. But it is faster through slow turns and much faster during rain and bad track conditions. Rally drivers, on the other hand, immediately took to AWD. Now, they will not race without an AWD-equipped car.
For the rest of us, a wide selection of AWD models, manufacturers and price ranges is available. Unfortunately, since every manufacturer of AWD vehicles is selling all it can build, there is no incentive to advertise. Most models are well-kept secrets.
One example of AWD is the Audi A6 Quattro, a $35,000 sports sedan that is a beauty. It just begs to be driven. It is fast, handles comfortably and has incredibly soft leather seats. Another little-known AWD sports car is the $35,000, 230 Bhp (brake horsepower), 3.3 liter boxer six-cylinder Subaru SVX LSi. Its radical styling and its AWD handling put it a world apart from its FWD cousins.
Among the less expensive two-seaters, Chrysler and Mitsubishi's joint venture, the Mitsubishi Eclipse GSX and its Chrysler twin, the Eagle Talon TSi, are real sleepers. Manufactured in Normal, Illinois, the turbo-powered and AWD-equipped GSX/TSi is only superficially related to the other models in its series. At $20,000 to $23,000, they offer the most fun per dollar of any sports cars I have driven.
In the mid-priced range, the GSX/TSi has a 320 Bhp big brother in the form of the $45,000 Mitsubishi 3000 GT VR-4 and its assembly-line twin, the $40,000 Dodge Stealth R/T Turbo. This twin-turbo V6 has AWD and all-wheel steering that make it especially agile, almost slippery. Any potential buyers should book track time to check out its performance envelope. In casual driving, I have found it to take curves on average 5 mph to 10 mph faster than non-AWD vehicles. Its California styling is a blend of traditional Italian bodywork and fussy Japanese high tech, and it favors luxury over performance. It is the first production car since the 1957 and 1959 Ford Skyliner to offer a power-retractable convertible hardtop. If it could go on a 1,000-pound diet and gain 20 percent more engine output, it would be as fast as it looks and a match for all but the superexotics.
Porsche now markets three AWD models, successors to the 911, which was first introduced in 1964. The base-model, $67,000 911 Carrera 4 Coupe is spartan but still has dual airbags and cruise control. Its stiff bodywork coupled with AWD make it difficult to give it challenging road situations. The six-speed, 270 Bhp version accelerates from 0 mph to 60 mph in 5.4 seconds and tops out on the track at 168 mph. For $8,000 more you can get it as a Cabriolet soft top. This spring, Porsche introduced a $100,000, 400 Bhp twin-turbo 911 model that will get to 60 mph in 4 seconds and top out on the Autobahn at 190 mph. This year's AWD models are sold out to the dealers and are in high demand.
For now, there is only one AWD superexotic--the 5.7 liter, 492 Bhp Lamborghini Diablo VT. More spacecraft than car, it has a top speed of over 200 mph. Its 12 cylinders give it more torque horsepower, and higher top speed without turbo boost. This is one very powerful automobile, so powerful that a four-camshaft 1,000 Bhp version of the engine has powered winning offshore racing boats and given new meaning to the term "land cruiser." With a suggested retail price at a daunting $220,000, it is available through a more affordable lease program of $52,000 down and about $3,000 a month.
AWD enhances the handling of all of these cars. It almost eliminates the possibility of the rear end breaking into a spin while going through a curve. AWD sports cars are much less boring and clichéd than SUVs. They get better gas mileage. They are fun to drive. The real downside of 4WD and AWD is the need to relearn the limits when switching back to the world of traditional 2WD sports cars.
The future is bright for those desiring 4WD. Manufacturers are gearing up new models and more manufacturing capacity. This should mean more choice, less time in waiting for back-ordered vehicles and even lower prices for buyers. Should mild winters prevail and the interest in sport utility models decline, the market would be glutted and manufacturers might have to initiate buyer incentive programs to move surplus product. Even if buyer demand remains strong, there would be an SUV war in the marketplace.
For the prospective buyer, this glut translates to an embarrassment of riches as every major luxury car maker but BMW, who already acquired Land Rover, plans to bring out new sport utility vehicles by 1998. This year, Toyota is bringing out its RAV4 compact SUV, already a best-seller in Japan. Not a replacement for the family station wagon, it is upscale competition to the compact Suzuki Sidekick as a fun car to take to the beach or as a personal SUV with better gas mileage for the daily commute. At the beginning of 1996, Lexus will introduce a six-cylinder Lexus LX450. Based on the Toyota Land Cruiser, it is targeted at "prestige, luxury, urban driving" couples who would shudder at scratching the lacquer on their new $50,000 car. Later in 1996, expect the Toyota 4Runner to get an overdue update.
Ford is also badly bitten by the SUV bug. It is toying with the idea of adding an AWD Taurus to its line. Expect to see models derived from Ford's popular Explorer badged by Mazda, Mercury and, in 1998, possibly even Jaguar. Aimed at the Range Rover market, the $50,000-plus Jaguar LUX is likely to have a sophisticated, height-adjustable, active-air suspension along with lots of leather, deep pile carpeting and polished wood trim. Lincoln is still considering its own 1998 luxury offering.
You must be logged in to post a comment.