- The added equipment, including the transfer case, drive shaft, powered axle, and other beefed-up components, adds thousands of dollars to the vehicle purchase price - generally on the order of $1500 to $4000.
- The added weight of all this equipment (500-1000 lbs) reduces gas mileage of the vehicle considerably, and also decreases cargo capacity.
- The added friction of the drivetrain severely reduces gas mileage as well.
- The added maintenance for these components adds to the cost of ownership, particularly as the car ages and major driveline components fail.
- Other components, such as tires and brakes may wear more quickly in AWD versions of vehicles.
Monday, July 19, 2010
Do you need or want Four-Wheel-Drive?
Four Wheel Drive and All Wheel Drive vehicles are very commonplace today - yet made up a small segment of the car industry as little as 20 years ago. Do you need four wheel drive in your vehicle? Or more concisely, does it pass the cost-benefit analysis test?
I've owned a number of four wheel drive and all wheel drive vehicles over the years. Ironically, when I lived in snow country, I never had one. Not even front wheel drive. We made do back then with rear wheel drive cars - often without posi-traction, and still got to work every day, even in a blizzard.
So why are four wheel drive cars so popular today? And do you really want or need one?
The first question is easier to answer. We are a wealthier country today than we were 40 years ago, so we can afford fancier cars, bigger boats, larger houses, giant televisions. And technology has made such consumer goods more "affordable" than before. Still more expensive, but now more affordable.
So four-wheel-drive, once limited to a few people who really needed it, has moved across the board as a commonplace option, like power windows and air conditioning (which 40 years ago, were also rare).
So today, we can "afford" these vehicles - or think we can. But do we really need the complexity and cost involved? What are the advantages to having four-wheel or all-wheel drive? For most people, it is largely an unnecessary expense, as we shall see.
Let me anticipate the response from some ignorant folk. "Well, some people need four-wheel drive to plow snow!" Well, duh. But a Subaru Outback isn't about to plow snow. Others might argue "Well, it snows where I live, I need an AWD car to get to work!" But as I noted before, many folks did just fine with rear wheel drive cars in the past. Why the sudden "need" for all-wheel or four-wheel drive?
And perhaps an explanation of these terms is in order.
Traditional Four Wheel Drive (4WD, 4x4) vehicles have a transfer case, usually two-speed, that can be engaged part-time. New Process Gear, a former division of Chrysler Corp., made many of these transfer cases. There is a 4x4 high range, 4x4 low range, neutral, and 2wd mode. Older Jeeps and 4x4 Pickup trucks used this type of system. A second drive shaft and a powered front axle - usually live, drove power to the front. Early models had manual locking hubs, which could be disengaged to reduce driveline friction. Later models had self-locking hubs which supposedly would engage and disengage automatically when four wheel drive was engaged or disengaged.
Such traditional systems had a 2WD mode, as they could not be driven in 4x4 mode on dry pavement, without chewing up tires or breaking driveline parts, particularly when turning. In the late 1970's GM offered a "full time 4WD" option on their trucks, and it tended to eat tires and get very poor gas mileage. Many upper-end versions of this traditional type of 4x4 may have posi-traction type differentials, or locking differentials, for extreme off-road use.
All Wheel Drive (AWD) is a somewhat different beast. These vehicles usually are permanently in four wheel drive mode, with no shift lever in the transfer case or high or low ranges. Usually, these systems use a Ferguson-type coupling (viscous) or a differential to couple the front wheels to the driveline, so that some slippage is allowed, which permits the vehicle to drive on dry pavement without chewing up its tires. The BMW X5 and entire Subaru line are examples of "All Wheel Drive" type vehicles. These are not four-wheel drive vehicles, even though they drive all four wheels.
The recent explosion in 4x4 sales has largely been of the All Wheel Drive variety, which is popular in many SUVs and mini-SUVs. Some are based on front wheel drive platforms, with the rear wheels being the added drive wheels. And some, like the Honda CRV, when offered in 2WD versions, simply remove the rear differential portion of the drive train, which is readily apparent to anyone following such a car.
Regardless of drive type - 4x4 or AWD - there are significant costs associated with owning such vehicles:
The gas mileage thing is what strikes most people, initially. Many Subaru buyers are chagrined to discover that their little politically-correct wagons are horrible gas hogs. Few Subarus top 30 mpg, with most getting in the range of 25 mpg or less (the "Tribeca" struggled to get 20!). In an era where a front wheel drive family sedan can easily get 30 mpg or more, this is appalling.
BMW offers AWD versions of some of its cars (the so-called "X-drive" which is just a marketing term), and many users report that brake life in such vehicles is reduced, perhaps due to the extra mass of the driveline components. Tire life may also be reduced due to increased scrubbing caused by AWD.
For long-term ownership, the doubling in complexity in the driveline may also be an issue. In addition to the transfer case (which is like having a second transmission) the number of drive shaft segements (and U-joints or CV joints) is doubled. Add in a front axle with CV joints, and there are even more modes of failure to contemplate. The simpler you can make a vehicle, the cheaper it is to own and maintain. Adding AWD adds to complexity, so the benefits had better be worth the cost.
Taken together, this results in a significant increase in the cost of ownership for a vehicle with AWD versus, say front wheel drive. Like anything else, is this additional cost offset by an additional benefit? That is the question you have to ask yourself. And for probably 90% of AWD and 4x4 vehicle buyers, the answer is a resounding "NO".
Why is this? Well, for starters, most people don't live in areas where it snows, or there are dirt roads or other quasi-off-road conditions. 95% of all 4x4 and AWD vehicles are never taken "off road" in their lifetimes, which is a good thing. Most consumer-grade vehicles (even Jeeps) are ill-suited for serious off-road adventures. AWD vehicles in particular, are not suited for off-roading, as they can easily get stuck and have little ground clearance. Tough-looking Jeeps with fording snorkels might look off-road capable. But try fording a stream in one, and chances are, you will void the warranty and perhaps short out one of the many electrical systems in the car.
In short, real off-roading should be done by real off-roaders, using vehicles suitably modified (or built) for that purpose. Taking the family grocery-getter on the Rubicon trail is a really bad idea, even if the vehicle claims to be a "Rubicon" model. Most of these 4x4 and AWD vehicles are sold on the basis of style, not capability. So AWD has become, in effect, the tail fins of our era.
But what about snow? What about it? As I noted before, my generation made do with rear-wheel-drive cars and snow tires for decades and still got to work on time. Many of these had no posi-traction, and thus in effect were one-wheel-drive cars in the snow.
And when the snow is so bad that they are closing the schools and places of employment, what is the point of having a 4x4? There really is no place to go, until everything thaws out. That's what I learned in Washington DC during the "blizzards" they have there. You (and every other jackalope with an SUV) might be able to drive around, but there is no place to go, as everything is closed. And of course, over-confident SUV drivers end up planting their cars in the snowbanks anyway. Four wheel drive is not impervious to snow!
The irony is, many AWD owners don't put on snow tires anymore, convinced that their AWD is an acceptable substitute for snow tires. So they slip-slide on "All Season Radials" and rely on AWD to save their butts.
A front-wheel-drive car with snow tires will handle snow far better than an AWD car with all-season-radials. And you can buy a set of snow tires for far less than the cost of AWD. If you factor in the extended life of your summer tires as a result, the cost of going to snow tires is really limited to the cost of extra rims and annual mounting. Comparing this to the extra gas used by an AWD, the maintenance and initial cost, you can see that a FWD car with snow tires is a far cheaper alternative.
And with modern traction controls, Front Wheel Drive cars with snow tires can really go places. Traction control has largely supplanted posi-traction differentials in the last few years, and it works really well. I recently drove my car to New York in February. I was taking it North to service it, and one item it needed was new rear tires. The summer tires on it were nearly bald. As luck would have it, it started snowing - heavily - as I arrived. Even with bald summer tires, on a rear-wheel-drive car, we made it home with no real issues - even driving uphill from a standstill. The traction control clanked and clunked, but it prevented wheelspin.
Still convinced you "need" All-Wheel-Drive? I'm not.
Some manufacturers claim that AWD improves handling, even on dry pavement or in the rain. Subaru is taking this tack nowadays, as its "beauty of all wheel drive" campaign seems to be faltering in view of their horrible gas mileage. While improved handling may be one advantage, I suspect that for most of us, the difference is negligible. Most people simply don't drive like boy-racers all the time.
I have owned a number of these vehicles over the years and still have two. I have my Ford 4x4 pickup, which has a traditional two-speed transfer case and locking hubs. I've had the truck for 15 years and used four wheel drive maybe a dozen times. It has been handy for pulling boats up slippery tidal ramps, but that's about it. (Note: Another approach to the boat issue is to mount a trailer hitch on the front of your vehicle, for boat launching purposes, so the rear wheels are above the "slime line" on tidal boat ramps).
It cost maybe $3000 more in purchase price than its 2WD cousin, back in 1995, and over the years, has used a few thousand dollars more in gasoline. It had about 500 pounds less in cargo capacity as well. So far, the driveline hasn't broken, but it has used two locking hubs (the self-locking hubs broke on a long drive to the Keys, and I replaced them with WARN manual locking hubs). If I was to buy a new truck today, I would buy a 2WD version, and save the money. (UPDATE DECEMBER 13, 2013: I did. A new Frontier 4x2 is about $5000 less than the comparable 4x4. The latter does "look tough" though, which is why young men buy them.)
Over the life of the vehicle, four-wheel-drive cost probably $5000 to $10000 more to own, in terms of initial purchase price, repairs, and mostly, gasoline. The benefits were limited, at best.
With other vehicles, I have had similar experiences. The BMW X5 is a nice tow vehicle for our camper. But the AWD feature is not something that I really use (particularly with its low-profile P255/55 R18 tires) and there really is no reason this car should get only 21 mpg on the highway. Shed of its extra AWD component weight and driveline drag, this vehicle could easily get 25 mpg.
Again, all costs, little benefit.
I recently sold my Jeep. A real one, not one of those plastic buggies they sell today. A 1948 Willys CJ-2A, re-powered with a small-block Chevy. While it was a true "go anywhere" type of vehicle, I found that it spent most of its time in 2WD mode. We rarely took it off-road, even though it had a twin-stick transfer case and positraction, front and rear.
Image sells vehicles, and when I was a young man, I succumbed to this and bought a Suzuki Samurai. Yes, it was a tinny piece of junk, and wholly unsuitable for general transportation on America's highways. But like many other young people, I was drawn to the image of the rugged 4x4 more than anything. The reality of a leaky, bone-jarring ride turned out to be an entirely different sort of thing, however, and I quickly sold it and bought a nice, air-conditioned Camry.
And image is what sells most of these vehicles. Soccer-Mommies want the powerful image of the rugged off-roader, even though they will never, ever take their Suburban even onto the lawn. Young men like the macho image of the rough, tough 4x4, replete with off-road accessories like extra lights and the aforementioned snorkel intake.
And that is the main reason people buy these things - image and marketing. And as we have discussed before, image and marketing are probably the worst reasons to buy any product. Very few of us "need" a four-wheel-drive or AWD vehicle, and yet these vehicles now comprise a large portion of auto sales.
Before you jump on the AWD bandwagon, consider the actual costs involved, both in terms of purchase price, and long-term ownership. Then weigh the alleged benefits. Chances are, the benefits are fleeting or non-existent. Chances are, the only real benefit is to your ego.
For general transportation purposes, a well-made front-wheel-drive car with traction control and anti-lock brakes (automatic stability control) is more than adequate for most people's needs. If you live in snow country, invest in a set of quality snow tires (all four wheels). You'll end up giving your AWD neighbor a ride to work, after he plants his "Outback" shod with all-season radials into a snowbank.