There are four main choices when it comes to wheel drive systems: front-wheel drive, rear-wheel drive, four-wheel drive or all-wheel drive.
1) Front-wheel drive (FWD)
Front-wheel drive is the most common system today, where the engine, transmission, final drive gears and differential are in a single unit under the hood and drive the front wheels.
- Allows smaller cars to have more interior space and trunk room.
- Weight of engine right over the drive wheels gives good traction in rain and snow.
- Typically more fuel efficient as the vehicle is lighter.
- Under harder acceleration, weight is transferred off driving wheels, reducing traction.
- Under harder braking, more weight is transferred to the front wheels, so they have to do the majority of the work. Therefore, the front tires and brakes wear out much faster.
2) Rear-wheel drive
With rear-wheel drive, the rear wheels move the vehicle and the front wheels provide steering. Most rear-drivers have the engine in front, but some have the engine at the back. Most pickup trucks use rear-wheel-drive, as do a handful of SUVs.
- Provides sportier, more controllable handling and better steering.
- Reduced mechanical complexity.
- More cramped interior due to driveline “tunnel” running the length of the vehicle.
- Trickier to drive in wet or snowy weather; easier to spin out in bad weather than FWD.
3) Four-wheel drive (4WD)
With basic four-wheel drive, which is found in many trucks, sport utility vehicles and military vehicles, the vehicle operates in two-wheel drive until four-wheel drive is engaged by the driver. Typically, this means the vehicle has rear-wheel drive until four-wheel drive is in operation.
- Best choice for serious off-roading.
- Least likely to get stuck in mud, dirt, or uneven terrain.
- Requires driver to manually engage 4WD; otherwise traction is not much better than a rear-wheel drive vehicle.
- Four-wheel-drive operation may be limited to off-pavement use.
- More rapid tire wear when operated in 4WD mode.
4) All-wheel drive (AWD)
Most AWD systems deliver all of the engine’s power to one pair of wheels (usually the front) until those wheels begin to lose traction. Then the system automatically begins to shift power to the other wheels until the car regains traction. All-wheel-drive is most commonly found in SUVs and crossovers, but is also used in sports cars to improve their handling.
- Entirely automatic; driver does not need to manually engage 4WD.
- Best choice for harsh weather; also works well on dirt and mud.
- Provides improved handling and better tire “grip” in sudden panic swerves.
- Greater weight and increased fuel consumption compared to front/rear-wheel drives.
- Faster tire wear than front- or rear-wheel drive systems.
- Not suitable for hard-core off-roading.