Dumb naming question?

[-]

rudbri93@reddit

generally*, 4wd indicates a system with a locking transfer case (no turning on hard surfaces) while awd is used for systems without a locking transfer case that operate on the street without binding.

*there have been cars that mix these up basically forever and it is absolutely not a hard and fast rule.

[-]

SailingSpark@reddit

Yes, my Land Rover Discovery 2 is AWD normally and once you lock the transfer case, is a classic 4x4. Unlike many 4wd vehicles, I can lock mine in high or low range, which is great for snow or sand.

[-]

Beardedwrench115@reddit

There's also regional differences, I've seen 4WD used to refer to both.

[-]

Total-Improvement535@reddit

GENERALLY

AWD is all wheels have power, all of the time

4WD is two wheels have power all of the time, until you engage the other two wheels, either manually or electronically

there are nuances to both depending on the set up, but this is the general rule of thumb

[-]

Most AWD cars are just FWD or RWD until slip occurs, then they transfer power to the other axle. Most Subarus send power front and rear all the time, with a limited slip mechanism in the center differential. My WRX STI send more power to the rear, has limited slip front and rear differentials, and if it slips can lock up the center differential. It also gets terrible gas mileage from the drag of all these parts.

[-]

One_Evil_Monkey@reddit

Yes there 100% is a difference.

Marketing terms have really muddied up the whole thing.

But generally speaking, in traditional 4wd, you as the driver would actually select between 2wd and 4wd. This is known as Part Time 4wd.

There is also what's known as Full Time 4wd. Which means you don't get 2wd. Full Time 4wd systems allow you to select between Hi range and Lo range though. Because they have dual range transfer case.

There is also Auto 4wd. Which allows you 2wd in normal operation, then the ECU will activate 4wd for you automatically when IT "feels like you need it". You have no control over when it activates or doesn't activate. Some Part Time 4wd systems have an Auto function that you can turn on/off so the ECU will activate when it thinks you need it when it's on but you can still manually select 4wd for times when YOU as the driver want the 4wd to stay on.

Part Time 4wd isn't meant to be put in 4wd and driven on dry pavement.

Then you have AWD. Which is essentially Full Time 4wd with the exception of it not having a dual range transfer case. Means you have 4hi only, there's no 4lo gear reduction selection. With most modern AWD systems the ECU will actually use the ABS controller to apply the brakes to one specific wheel to make the opposite wheel use the traction it has and a lot of them will also use the ECU to control the transfer case to shift power output between the front and rear as needed.

[-]

Automatic_Mulberry@reddit

AWD is more computer-controlled, and dynamically allocates torque from side to side and from front to back, determined by the slippage of each wheel. It uses clutch packs to engage and disengage each wheel/axle.

4WD is actual gears, actuated by the driver. There can be an option to lock the differentials, as well, so that all of the wheels will move together in all circumstances.

AWD is typically better on roads and in less extreme conditions. 4WD is typically better off road and in very bad conditions, but is less good on road. For example, driving in 4WD on dry pavement can chew up tires and such.

[-]

One_Evil_Monkey@reddit

Some systems are computer controlled. Mainly modern systems.

But care to explain my '79 GMC High Sierra that ran in 4hi for normal operation? Not a single computer in sight on that truck. It was purely mechanical with three open differentials. One on each axle plus the center differential in the transfer case. But you could lock the center diff, try turning on dry pavement like that and you'd have exploded bits of transfer case. Haha

[-]

VulpesIncendium@reddit

Although AWD can work the way you describe it, it's usually a lot more simple than that. Early AWD systems simply had three open differentials: engine to transmission to center diff to front and rear diffs. Better systems use mechanical limited slip differentials. Most modern AWD systems have some sort of limited slip center differential and open diffs at the front and rear, and simply use the brakes to force power to go to the wheel with traction if one starts spinning.

[-]

gravelpi@reddit

Maybe in the last decade it's computers, but before that there were plenty of purely-mechanical AWD systems out there.

[-]

revocer@reddit

4WD: specifically for off-road vehicles, where you kinda have to know what you are doing not to eff up the vehicle.

AWD: specifically for on road vehicles, and the computer controls it, and a chimpanzee can run it.

[-]

9BALL22@reddit

There are definitely differences.

[-]

pm-me-racecars@reddit

Nowadays, it's mostly marketing.

There is a proper difference, and I'm sure that all the other commenters have told you, but the people who make the marketing stuff don't care about that difference.

[-]

Miliean@reddit

What is the difference, if any, between all-wheel drive and four-wheel drive? Is it just marketing or is there a real difference?

There is 100% a real difirence, however it is muddied with marketing terms.

As a general rule, the main difirence is if you need to select it or not, aka is it driver controled.

Most 4WD systems are driver selected. You pick when to be in 4WD mode or 2WD mode. Often time there's also additional choices such as locking differentials. 4WD is really good for off roading, like real off road off roading, like driving in a dry riverbed or up the side of a mountain kind of off roading. Normally you see 4WD in pickup trucks, SUVs based on pickup trucks and things like Jeeps.

AWD on the other hand is a bit more of a mixed bag, but the unifying factor is that it's not generally driver selectable. The car is waither always in AWD mode, or the computer picks when to engage AWD mode, not the driver.

AWD is really good for getting traction on a road where you might otherwise get stuck. Going up a hill in the winter time, AWD is your friend. Driving on a gravel or dirt road in the wet or snow, AWD is your friend. It's not generally used for "off roading" per say. It's more like, poor conditions but still on a road.

An important thing to note, basically every manufacturer has their own variant of AWD and they all work a bit differently. Subaru for example is the "always on" kind, Honda for the most part is a front wheel drive vehicle where the car computer can send some of the power to the rear wheels as needed.

[-]

Prize-Lychee7973@reddit

the "virtual 4wd" awd systems are the drivetrain equivalent of the paddle shifters being "manual input".

[-]

wsxdfcvgbnjmlkjafals@reddit

https://www.google.com/search?q=difference+between+awd+and+4wd&rlz=1C1GCEA_enCA1110CA1110&oq=difference+between+AWD+and+4&gs_lcrp=EgZjaHJvbWUqDAgAEAAYQxiABBiKBTIMCAAQABhDGIAEGIoFMgYIARBFGDkyBwgCEAAYgAQyBwgDEAAYgAQyBwgEEAAYgAQyBwgFEAAYgAQyBwgGEAAYgAQyBwgHEAAYgAQyBwgIEAAYgAQyBwgJEAAYgATSAQg0OTI2ajBqN6gCALACAA&sourceid=chrome&ie=UTF-8

[-]

Argentius99@reddit

At least by convention, "4WD" means a truck-style 4-wheel drive system with a mechanical center transfer case sending power to all 4 wheels at once, usually on demand with a button or switch. It's for off-roading and heavy-duty occasional use.

"AWD" means a car-style "All wheel drive" where a viscous coupling, similar to an automatic transmission, sends powers to all 4 wheels, all of the time. Uusally can't turn it off. It's for traction and all-day, everyday use.