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December 19, 2011


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RT Kramer

Thank you Jim! I have always felt the same about the whole drive wheel word game. I guess I also feel that some of the supposedly "AWD" vehicles should be classified as "partially-four wheel drive" simply because they can not supply equal power to each wheel. For getting through the snow and up the hills in my neck of the woods I still like my old true "4x4" Wagoneer with it's limited slip rear axle and the air locker axle I had installed in the front years ago. But progress must march on of course. Siiigh... yes, I'm just old I guess. RT in upstate NY.


You took a lot of time to sound your age. You could of just typed, "I'm old and new things scare me," in all caps and you would of achieved the same end. It's a patented phrase for proprietary engineering.

John B

Thank you Jim for explaining that to the Great Unwashed and putting the Know-It-Alls in their place! The only time an "all-wheel-drive" is not a "four-wheel-drive" is when it has more than four wheels. Oh, and I hate it when people talk about four-by-fours. What the heck is THAT really supposed to mean?


Hey Jim:

There are many forms of "AWD". Subaru and Audi are the only manufacturers who do this correctly.
Seems many car companies have there version of how they think this should accomplished. Check out the various website for details or better yet drive and AWD Audi for a year. There system just works. There are subtle differences if you dig deep into the specs.


You criticize the term "all-wheel drive" for being imprecise. Well, as you've just proven by your examples, the term "four-wheel drive" is even more imprecise without further qualification. Sure, it obviously means four wheels, all driven, but how? Does it mean part-time or full-time, does it mean manually-engaged or automatically-engaged? At least "all-wheel drive" usually implies an automatically-engaged full-time system.
"Four-wheel drive" alone does not tell you, which is likely why someone invented the term "all-wheel drive".


Funny thing Jim, you claim you are an engineer, but PEO doesn't have you on record as a P. Eng. For someone making an argument about being precise with language, you should be more careful, as the term engineer and its use is regulated under the Professional Engineers Act. Using the title without being one is worse than the marketing "bafflegab" you disdain.


Here here, telling it like it is. KUDO's

n. platt

As usual Jim you make too much sense when you write. Many drivers look at their cars as engineering marvels and have little or no idea what goes into building a car. Many moons ago I worked at a car dealership and it was a real learning experience both on the selling and propaganda sides. I thought I knew cars pretty well but not only did I not know the engineering part very well, I got confused when it came to the symantics of all wheel, four wheel drive and any other designation of a car maker's marketing. What it boiled down to for me was, having really good tires to help you stop rather than worrying about that one time you got stuck in a snow bank.

Caw mentor

The difference between 4 wheel drive and all wheel drive in most vehicles on the market is not whether they are full time or part time, but rather if the vehicle is equipped with low gearing. Only the 4 wheel drive vehicles have the low gearing for going slow over off road terrain, where they both drive all wheels for a little less slipping and sliding on mud and snow on the road.




Congratulations on taking a stand against marketing attempting to make up terms for things that sound 'sexy' while not being at all accurate.


Jim, you're missing one main point - a locked center differential on the traditional 4x4 vehicles. This, to me, is what highlights the difference between AWD and 4WD - the ability to drive on dry pavement without driveline binding, wheelhop, etc, are what define AWD in the place of 4WD.

You're correct, however, that this really is more of a marketing issue than an engineering one, simply because either term is generic enough to accurately represent a vehicle where all wheels are driven. The SAE doesn't have a position on 4WD/AWD, so it really doesn't matter, one mechanical engineer to another.


I drive a Jeep, my brother drives an Acura MDX. Mine has full time 4x4, or 4 wheel drive, or all full-time all wheel drive. We were both surprised to realize that his MDX does not in fact have 4-wheel drive, but rather that it has some kind of automatically engaging drivetrain that can drive certain wheels when needed and not at do it at other times.

Four wheel drive, 4x4, or all-wheel drive terms being used to describe a part-time 4x4 system that engages on its own when instability is detected, would be false and misleading advertising.

Can you imagine the trouble "true 4x4" Jeep owners would get into if they took a part-time 4x4 onto an off road trail? Yes, lawsuits would follow, be sure.

four wheels, all are driven, all the time = full time four wheel drive. Anything less is a lie. Couldn't be simpler.


You can also add true 4 wheel drive where the vehicle has locking differentials front and rear as well as the transfer case. These came in mid 90 Toyota Landcruisers, Mercedes Gelandewagen, and the Jeep Rubicon. There may be others. This system is the only one where the capability of having all four wheels drive at the same time with full power at every corner. The downside is that they are difficult to drive on hard surfaces with the diffs in the locked position. Unlocked it is the same as what the writer describes as "manually-engaged part-time four-wheel drive".


Until you go to buy a car or get insurance. "4 Wheel drive" and "All wheel drive" do have specific meanings, one will also burn more gas then the other as an "all wheel drive" being engadged ALL the time will burn more gas than a "4 wheel drive" of the same model. Sorry but a pointless attempt of "I'm smarter than you".


Glad you cleared that up Jim.
Thankfully the marketing people haven't yet hit on other useless terms like "every wheel drive", "multi-wheel drive", or LWD ("lotsa wheels driven").


most of todays 4 wheel drives are not even 4 wheel drive
yes both the front and rear are powered.. but unless you have a locker in the axles you only get limited slip 4 wheel drive..
meaning power is only transfered to one tire in the front and one in the rear your not getting true 4 wheel drive.. Like you would on say the Jeep rubicon when you engage the locker after 4 wheel drive is engaged...


Hair splitting at its finest. You know what all wheel drive implies, and what 4 wheel drive implies. Anyone who pays attention to vehicles knows what the differences of the terms means. But you are an "engineer" and are above the names the industry has chosen for the two drive systems. Suck it up, and accept the names...that's all they are: names. Calling an all wheel drive a 4 wheel drive only confuses people who don't realize you are just being anal about the wording.

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