Sport Utility Vehicles – Hybrid vs. Diesel SUVs

By dancurranjr On December 28th, 2009

As more diesel and hybrid vehicles enter the market, drivers increasingly want to know which is better. This is an especially big question for sport-utility fans who feel they could easily justify owning one of the large vehicles if only it could match the fuel economy of a car.

Of the diesel and hybrid SUVs I have driven – there are only a dozen or so available — the Toyota Highlander Hybrid Limited and Volkswagen Touareg TDI come closest to combining midsize-car-like fuel economy with the size and cargo capacity that make SUVs appealing. Most other models are either too small to give drivers the high-riding sense of command they seek, or don’t come close to having decent fuel economy.

The Highlander and Touareg are well matched in price, power and practicality, and are about the same size. But the $41,020 Highlander runs on hybrid technology and the $42,800 Toureg on a diesel engine. The Highlander also offers a third-row seat the Touareg lacks, but it is too small for convenient regular use.

Each has a relatively small six-cylinder engine that still manages to power a large vehicle competently. The Touareg’s engine is typical of most diesels — they are generally good at getting a vehicle moving from a stop, and have more power at low speeds than gasoline engines of similar size. Diesels don’t have as much high-speed horsepower, but their low-speed muscle, or torque, is a better fit for the way most people drive.

The Highlander’s hybrid drive system uses an electric motor to provide similar torque that assists the gasoline engine under hard acceleration. The result is that neither gives its driver that frustrating, underpowered feeling.

On paper the Highlander seems like the easy winner because its estimated fuel economy is 27 miles per gallon in city driving and 25 mpg on the highway, compared with the Touareg’s 17 mpg in city driving and 25 mpg on the highway. But in typical everyday driving I found the two to be much closer in performance and fuel consumption. During long highway trips, both clawed their way to 27 miles per gallon, which is remarkable for big, heavy SUVs.

But I found that the hybrid’s urban fuel economy usually fell short of its estimate unless I drove in a slow, plodding way that makes the most of the hybrid’s electric motor. The problem is this driving style annoys other motorists, especially those caught behind you.

The Touareg diesel usually performed a bit better in the city than its estimate suggested, though it never came close to matching the hybrid in pure stop-and-go city driving. The Highlander’s ability to run on its electric motor alone at lower speeds lets it excel in the slow, choppy driving conditions at which gasoline and diesel engines are least efficient.

In everyday driving, I avoided unnecessarily fast starts and tried to drive smoothly, but did not truly strive for top fuel economy. The result: About 24 miles per gallon overall in both the Highlander and Touareg. However, when I tried a little harder to squeeze extra miles out of each vehicle by obeying speed limits, planning suburban routes to avoid stop-and-go driving and coasting whenever possible, the Highlander began to edge ahead. Both SUVs have trip computers that keep track of average fuel economy, and the Highlander’s seemed to respond more readily to small changes in driving style. If you work hard to hone your driving technique to maximize fuel economy, the Highlander seems to work with you and is therefore more rewarding to drive.

The biggest difference between these vehicles lies in their mechanical feel on the road. Other than using diesel fuel, the Touareg feels conventional. Its engine rumbles steadily and its six-speed automatic transmission shifts with a rhythm that most drivers will find familiar.

The Highlander, however, has a continuously variable transmission that smoothly varies its drive ratios in a way that lets the vehicle’s speed build without the distinct steps of a transmission with conventional gears. The feel is seamless, but less engaging. The engine often sounds like it is laboring, but “CVTs” tend to be more efficient than typical transmissions.

Drivers who are especially fond of SUVs with traditional power plants and familiar mechanical layouts may still prefer the way the Touareg feels on the road and responds more sharply to the throttle, while finding the Highlander a bit off-putting. Still, I got used to the Highlander’s transmission quickly and liked the way it smoothed out its overall ride. I also appreciated that the Highlander weighed several hundred pounds less than the Touareg despite carrying two power systems (electric and gas). Drivers who frequently tow heavy loads will almost surely pick the Volkswagen for its 7,716-pound towing capacity, compared with a rather weak 3,500 for the Toyota.

I would happily drive either vehicle every day. Both run smoothly, handle well and are comfortable for long trips. But the Highlander always felt like Toyota took more time and care in putting the car together. And then there are the numbers — the Environmental Protection Agency’s average fuel cost estimate for the Highlander is $1,542, compared with $2,100 for the Touareg diesel. While such estimates aren’t perfect, they are especially helpful when comparing vehicles. In the end, the Highlander does a better job at mixing the often incompatible elements of SUV size and space with small-car fuel economy.

SOURCE: Wall Street Journal

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