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Not necessarily. Depends upon the 4x4 set-up in a vehicle, the transfer case, and the axle drives.
There are many "shift on the fly" variants to engage the transfer case and the front hubs on 4x4 vehicles.
For many, the power delivery is no different than driving a 4x2 (RWD only) vehicle until you engage the 4x4 system.
Of course, having that equipment does add to the weight of the vehicle all the time. Hence, likely decreased fuel economy. Plus, many 4x4 vehicles have a higher/bigger stance which adds windage compared to their 4x2 stablemates.
There are some 4x4 vehicles that are full-time, so they do get the fuel penalty even when the 4x4 isn't needed.
Not necessarily. Depends upon the 4x4 set-up in a vehicle, the transfer case, and the axle drives.
There are many "shift on the fly" variants to engage the transfer case and the front hubs on 4x4 vehicles.
For many, the power delivery is no different than driving a 4x2 (RWD only) vehicle until you engage the 4x4 system.
Of course, having that equipment does add to the weight of the vehicle all the time. Hence, likely decreased fuel economy. Plus, many 4x4 vehicles have a higher/bigger stance which adds windage compared to their 4x2 stablemates.
There are some 4x4 vehicles that are full-time, so they do get the fuel penalty even when the 4x4 isn't needed.
Or in a popular transfer case in many Jeep and Dodge vehicles:
2WD (Rear wheel drive)
4FT (4WD, shafts not locked)
4PT (4WD, shafts locked)
N (for being towed by another vehicle)
4LO (2.3:1 reduction, shafts locked)
Front and rear drive shafts are locked in 4 part time and 4 lo. Separately, whatever differentials you have (LSD in the rear or otherwise) are what they are. These two settings just basically force a hard 50/50 torque split between front and rear axles.
FWIW, my Durango's full-time setting says "AWD" yet all 4 wheels are constantly engaged in a 48/52 torque split. Open front differential, limited split rear diff, 3.55 ratio.
car? Unlikely it will be a 4WD (usually designated for trucks / tractors - FIXED engagement) optional from day one (late 1800's)
AWD usually is 'metered' / proportional... (as needed) traction control. (modern version).
Handy if you are in snow country, but at a cost (economy and Maint)
Really depends on your use and preference (and total miles / yr in hazard conditions)
I lived / drove 20+ yrs in Colorado and other mtn states with 2wd.
My parents had MASSIVE snow and mtns, but NEVER had 4wd or AWD.
Some of the Toyota RAV4 models are AWD while some others 4WD. The 2010 RAV4 V6 my wife drives is a 4WD vehicle. In this case one can engage or lock the 4 wheels with the push of a button on the dash, which in turn disengages automatic 4WD system and keeps it on manual though a speed of 25MPH. If 25MPH is exceeded, the system automatically disengages the manual 4WD, and switches to fully automatic.
4WD = RWD until the driver actively selects 4WD mode by engaging the transfer case to split the power between the front and rear axles. Found almost exclusively in pickups these days, possibly some old-school body-on-frame SUVs too. Best for deep snow, mud, rock-crawling, and the like. Not good for dry pavement unless you like scrubbing the hell out of your front tires.
AWD = "always on" meaning either the car is always in AWD mode, or increasingly, the car defaults to 2WD mode (usually FWD) and decides on its own to send some power to the other axle when the need arises such as when it detects the primary drive wheel slipping or under heavy acceleration/high-load cornering. This is what most AWD-designated cars and unibody CUVs/SUVs have.
Some SUVs/CUVs combine a bit of both, an AWD system capable of locking the center differential at low speeds. These are still generally considered "AWD" since there's no time when it's exclusively in 2WD-only mode.
This is the best explanation at Bitey writes about the transfer case in 4WD.
AWD is good if you are buying a car/suv for road use in a wet and/or snowy climate. It adds traction when needed to prevent you from losing control.
4 wheel drive is good if buying a truck/suv in which you intend to drive some off road, such as beaches, muddy/sandy back roads, wet fields, etc... and it can be used on the street as well in snowy/slippery conditions. Conventional 4 wheel drives also have a low range which doubles your final gearing to a slow/torquey crawl, great for slowly crawling down a steep hill without having to touch your brakes.
Then there are the systems which are full time 4 wheel drive (such as jeeps quadratrack) in which a center diff sends power to either the front or rear axles, but can be locked to make it like a conventional 4x4. The systems I'm familiar with have a low range as well. It was (perhaps still is) popular in snowy climates on vehicles such as the original, full sized Wagoneer/Cherokee
My 2005 Dodge Durango has a selector with 3 choices:
Full-time AWD
4 WD Lock
4 WD Lo
It uses both AWD and 4WD. Thus, AWD and 4WD are not mutually exclusive in a vehicle. It's never been stuck in the snow. (This past winter we had over 400 inches of snow measured in our driveway in Deer Valley over the course of the winter.)
My 2016 Acura MDX has full time AWD (they call it Super Handling-All Wheel Drive) has been stuck when my Durango can go right on through.
At the end of the day, make sure you get snow tires for cold winter weather. They help quite a bit with traction when the temperature drops below about 40 degrees F or when the roads are icy/snowy/slippery.
And, remember this: Both AWD and 4WD help you "go." Neither help you "stop."
Yupp.. AWDs for Rav4s, CRVs and of the likes is meant to get some basic traction for the rear wheels when stuck. Helps out in the city and stuff when there's alot of snow. Not in Mountains or offroads when traction is more needed. Subaru is the only 'real' mainstream AWD for smaller CUV type segment
This vid shows the difference between a Subaru and all others.
Yupp.. AWDs for Rav4s, CRVs and of the likes is meant to get some basic traction for the rear wheels when stuck. Helps out in the city and stuff when there's alot of snow. Not in Mountains or offroads when traction is more needed. Subaru is the only 'real' mainstream AWD for smaller CUV type segment
This vid shows the difference between a Subaru and all others.
youtube.com/watch?v=0_MXK2nzt2Y
The great majority on vehicles on the road in Alaska aren't AWD like the Subaru, but AWD vehicles such as the CRV, trucks, FWD and so on. What is most common with automobiles during the winter months in Alaska is having the proper tires for road conditions.
That said, some 4WD and AWD systems allow for disabling the automatic AWD and 4WD functions so that the axles are locked. For example, the 2010 RAV4, and the 2009 Forester (I owned both, but traded the Forester for the RAV 4 because of the infamous Subaru head gasket problem).
1. Anyway, lets say that I was pulling a boat-loaded trailer out of the water with the 2009 Forester. In this case I didn't want the automatic AWD system engaged, because it would cause the rear end to fishtail if one of the rear tires lost traction. So I would disable the automatic traction control with the push of a button.
2. The same thing as above is accomplished with the 2010 RAV4, except that in this case the axles are locked and stay that way up to 25 MPH. Exceeding 25MPH would automatically disengage the manual 4WD and engage the automatic AWD system.
The videos you see on you tube are mostly advertisements, and usually rigged. For example, look at the "Subaru versus rollers videos on "youtube," and you will notice all kinds of traction systems of other vehicles where the Subaru traction system is superior. But regardless of which automobile you buy, I doubt that you are going to drive it on a set of rollers, off-roading over large rocks, up on ramps, and so on. See if you find an old "subaru versus roller" video where only two rollers are placed under the right side tires. In this case the subaru used for that video was completely stuck on the rollers. But if it had been the 2009 Forester on the same two rollers, I would have disabled the automatic traction system and driven off the rollers.
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At the end of the day, make sure you get snow tires for cold winter weather. They help quite a bit with traction when the temperature drops below about 40 degrees F or when the roads are icy/snowy/slippery.
And, remember this: Both AWD and 4WD help you "go." Neither help you "stop."
Yep, AWD and 4WD help with applying power, that is, accelerating. They don't help with braking and they don't help with cornering (unless you're accelerating through the corner). If you're going to be driving in snowy or icy conditions, winter tires are still important for safety - if you care about not spinning out and and not sliding off the road. In fact, I feel that winter tires are more important than AWD/4WD in snow and ice road conditions.
Start with where do you live and drive. For most folks in the sun belt, 2WD will be totally adequate and cheaper to buy. The snow belt is another matter.
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