All About Front-, Rear-, Four-Wheel and All-Wheel Drive

Edmunds.comEdmunds.com Member, Administrator, Moderator Posts: 10,316
edited June 2015 in General
imageAll About Front-, Rear-, Four-Wheel and All-Wheel Drive

Everything you need to know about how all-wheel, four-wheel, front-wheel and rear-wheel drives work, and which is best for you.

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  • rherhe Member Posts: 2
    What is the difference between Honda's RealTime AWD and Acura's SH-AWD? Does the Acura system have right to left side torque vectoring and Realtime not?
  • blastermaster5blastermaster5 Member Posts: 1
    edited May 2015
    rhe said:

    What is the difference between Honda's RealTime AWD and Acura's SH-AWD? Does the Acura system have right to left side torque vectoring and Realtime not?

    The RealTime 4WD is two different systems. The System commonly used on the Honda cars uses a viscous clutch to provide a inkling of torque to the rear wheels. This works fine on level roads in winter weather, but provides no help on hill starts, and no torque vectoring. This is found on the Honda CR-V, Element, and Pilot. The other RealTime 4WD is the VTM-4, specifically the Honda Ridgeline 4WD, which is a very unique system. It has a special transmission and a locking rear differential, which can lock at speeds under 6 MPH, and provide 4WD at speeds under 18 MPH. After that, it is a front wheel drive pickup truck, and probably the only example of such a thing.

    Super Handling AWD is Honda's performance AWD. It uses torque vectoring to eliminate understeer when pushing the car past its limits, and can send full torque to either of the rear wheels (or both), like the VTM-4 system, but SH-AWD does so at higher speeds.

    While none of these systems are designed for offroading, the VTM-4 and the SH-AWD are the most capable systems for hill starts and worse than level road bad weather. The RealTime system is useless, as is any car with a similar front wheel drive + viscous clutch to rear setup.
  • adam111adam111 Member Posts: 1
    Front-wheel-drive systems are less complex and thus cheaper to make than other drivetrain systems, so economics has played a role in their growing use. FWD systems also tend to wear out faster than the less-complex RWD systems.
    These two sentences have me confused. It seems like FWD would be less complex than RWD because it lacks the driveshaft and rear differential.
  • anomalyanomaly Member Posts: 1
    edited January 2016
    Rear wheel drive is better up hill, snow or no snow, than Front wheel drive. The CG of the car shifts the weight toward the rear axle when on an incline, and more weight over the tires = more traction. Also all cars today have stability / traction control..(2012 up models) Spinning out / losing control is pretty much impossible now.. Go try it in a parking lot if you don't believe me! A rwd car has closer to 50/50 weight distribution these days, so put it on an incline and more goes to the rear. A Front driver has 60% up front, up hill that number would be reduced. It's further reduced by the forces of acceleration. Also with passengers in the car, or weight in the trunk, a RWD has even MORE traction in the snow. If you can't get up a hill in a front driver, try it in reverse. It works because of the same principle! FWD saves interior space and money for the manufacturer.. It's not better or safer at all.

    Picture a fully loaded front drive minivan going up a snowy fill. It's probably got 60% of the total vehicle weight (incl passengers and cargo) on the REAR wheels at that point, and only about 40% on the front. Factor in acceleration forces (which are low, but still present, on slick surfaces) and you have spinning tires up front. This is also why the front brakes on a bike OR a car are much more effective than the rear (when going forward).. That's the weight transfer effect.
  • quickchangequickchange Member Posts: 1
    Good article, but did not address vehicles with a front and rear axle with or without a posi-trac or locked differential. Without and in 2WD, you have one drive wheel in a slippery conditions and in 4WD you would only have 2 wheels diving. Experienced that situation trying to move my boat in a level yard that was wet from rain. Made a mess instead of being able to move with 4 wheels driving. I guess that 4X4 label on the side is misleading !
  • jelnnnnjelnnnn Member Posts: 1
    What's better AWD on a Toyota RAV4 SXL Hybrid or Front wheel drive on a Toyota RAV4 Limited, driving is on streets in a northeast US climate?
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    There's a lot of variables in this question. My formula for driving in snow is that it requires 50% driver, 25% car and 25% tires for the greatest success and safety. So an experienced driver with a FWD and 4 (yes 4) good snow tires is going to do better than an inexperienced driver with AWD and all-seasons.

    Another variable is topography. AWD is only better than FWD in one thing---acceleration. It doesn't help you brake better or steer better---that's what the driver and tires do for you. So if you're doing any hill climbing or driveway climbing in your commute, an AWD with good snow tires will outperform a FWD in most cases.

    So you have to make some assessments here. How good a driver am I in snow? Do I have a lot of confidence? What type of terrain am I going to experience most of the time? Am I okay with running both "normal" and snow tires and switching them out every spring?
  • russkie2russkie2 Member Posts: 2
    I watched Top Gear America and the host said about a car smth like "rear wheel stair and rear wheel drive monster". If someone saw this episode, can he explain what did he mean by "rear wheel stair"? Is it about " "steer" a rear-wheel-drive car with the gas pedal " as written in this article and "stair" is strangely pronounced "steer"?
  • PF_FlyerPF_Flyer Member Posts: 9,372
    With the word monster in there, I'm thinking they may have been talking about trucks. There was an episode where they modified cars with monster truck tires and suspensions. From Wikipedia:

    Title: "Texas" Original Airdate:July 24, 2011
    Feature: Tanner, Rutledge and Adam wrangle, haul and race their way across Texas in a crazy attempt to find an alternative to the pickup with 2 doors. The catch is that they only get $2000 to buy a car. Adam chooses a 1975 Ford Maverick and claims it is related to the Ford Ranchero. Tanner chooses the BMW 325e and says it has more technology than a 2011 pick-up. Rutlege chooses a 1991 Mazda Miata and he claims that it is the perfect replacement for a truck.

    Challenge 1: Cattle Drive. All three hosts must lead and protect a large herd of cattle by taking point. They're not allowed to lose any of them. There's no clear winner, but Adam claims victory due to the steers mostly following his Maverick.
    Challenge 2: Manure hauling. Each host modifies his car to carry a huge load of fertilizer (cow manure). The biggest load wins. Adam cuts off the roof of his Maverick, turning it into a crude version of the Ranchero. Rutledge puts the top down on his Miata and is nearly buried beneath his load. Tanner puts plastic buckets on the roof, sides and front of his BMW. Despite this, he ends up with the lightest load. Winner: Adam
    Challenge 3: Monster Truck Racing. All three cars are modified with monster truck tires and suspension and are raced around a track. Adam takes the early lead but his engine overheats and burns out. Rutledge actually loses a wheel, leaving Tanner to finish the race. Winner: Tanner[3]
  • russkie2russkie2 Member Posts: 2
    No, that was about Mercedes AMG GTR in Top Gear America, not Top Gear: USA, Tom Ford was talking, sorry for not giving this information
  • perfdba99perfdba99 Member Posts: 1
    do 4 wheel drive trucks sit higher off the ground than 2 wheel drive? i have a 4x4 chevy silverado and want to find a lower full size truck for ease of entry. thanks
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