Drive It Forever

Dear Bob: My husband and I have been considering the purchase of one of the following vehicles: a Toyota RAV4 or a Honda CRV. My husband currently has a 4X4 Ford Ranger, and feels that only another 4X4 will do the job for him.

Are all-wheel-drive vehicles comparable to 4X4s? We are not quite clear on all-wheel drive vs. 4X4. He does do some offroad driving, but I read that AWD will get better mileage.

What would be your recommendation?

Thanks.

— D., via e-mail

A: The two vehicles you mention are fairly comparable in fuel economy. The Toyota is EPA-estimated at 22 mpg/city and 27 mpg/highway, with either a standard or automatic transmission, while the Honda is rated at 22/26 for the manual shift and 21/25 for the automatic.

The key difference between all-wheel drive and part-time four-wheel drive is that, in order to engage power to all wheels in part-time four-wheel drive, the driver has to shift another set of gears to activate it. All-wheel drive, on the other hand, is a permanent feature in which all four wheels supply power all the time and there is no transmission to shift.

But the differences between all-wheel drive and full-time four-wheel drive depend on the manufacturer. True all-wheel drive distributes power to all four wheels all the time, exactly the way true full-time four-wheel drive does. Some manufacturers also use the term “full-time four-wheel drive” to describe the traction-control system that delivers power to the rear wheels whenever the front wheels lose traction, but that really isn’t accurate.

The Honda and the Toyota you’re considering employ different four-wheel-drive systems. For Toyota it’s simply — and correctly — “full-time four-wheel drive.” Toyota’s system uses a viscous coupling-center differential to split the power 50/50 between front and rear axles. If slippage occurs at either axle, the computer automatically transfers more power to the other axle. There is no transfer-case shifter inside the vehicle, because the full-time 4WD is engaged automatically. The system supplies power to all four wheels at all times, even on dry pavement. At no time is the vehicle in two-wheel drive.

Honda calls its system “Realtime 4WD.” Like the unit in the RAV4, it operates automatically and only when needed, and requires no intervention on behalf of the driver to engage or disengage it. The difference is that it sends power to the rear wheels only when there is insufficient traction at the front. At all other times you’re driving a standard front-wheel drive.

So the main difference between the RAV4 and the CRV is that the CRV is a two-wheel-drive vehicle when the four-wheel drive is not operating, while the RAV4 is always in four-wheel drive — that is, power is always being delivered, in varying degrees, to all four wheels at the same time.

The RAV4 is a true full-time 4WD, in short, while the Honda’s Realtime 4WD comes into play only when there is insufficient traction up front. In essence it’s a part-time four-wheel drive that needs no driver activation.

The two vehicles get comparable gas mileage, so it seems that your choice should depend on which system you want. Over and above that question, you’ll want to consider price, warranty, dealership and, after thoroughly test driving both, which vehicle you prefer in terms of handling, performance, driver and passenger comfort, roominess, storage, overall look and other utilitarian concerns.

Have fun!

AMERICAN DRIVERS FIGHT BACK

Here’s a tip that will help you get better gas mileage while fighting terrorism and cutting our nation’s dependence on Mideastern oil:

The ongoing hullabaloo over the righteousness of driving SUVs and other high-fuel-use vehicles is cause for some thought.

This column has never asked that you trade in your SUV or pickup for a small vehicle that gets 50 mpg. While that might be nice, I know that for many people this isn’t practical, nor will it be any time soon.

“American Drivers Fight Back” asks only that, no matter what kind of vehicle you drive, you drive it responsibly and that you do so with conservation in mind. This is not some Johnny-Come-Lately brainstorm on my part: I have been urging conservation of our natural resources ever since the first gas crisis, back in the early 1970s.

Even back then, it was clear that conservation was the wave of the future. I dedicated my 1978 book, “How To Get More Miles Per Gallon,” as follows: “For my son Kyle and all the children of his generation, with the hope that we have the foresight to conserve fuel today so that they may know the pleasure and responsibility of driving a car in the future.”

A number of years later, in a new edition of the book, I added, “It is still my hope that we will learn to be efficient and responsible drivers and conserve both fuel and the planet we live on.”

We now have more compelling reasons to conserve fuel, and if it’s possible for you to shift to a more fuel-efficient vehicle — or, if you have more than one vehicle, to drive the most fuel-efficient one as much of the time as possible — it’s definitely a good idea to do so.

If that’s not possible, do your best to conserve fuel by driving intelligently. It’s better to drive your gas-guzzler well than to throw up your hands and figure that you’ve already lost the battle.