Drivetrain – What’s the Difference?

One of the primary characteristics of any used car you’ll want to buy is it’s drivetrain.  What this means is; how is the car propelled forward?  This may seem like an odd question to ask, after all you just want it to go!  But which wheels push the car make a huge impact on control, driving and even gas mileage.

Rear Wheel Drive/Front Engine – The most common and simple layout for a car, this is how most cars were made in the last century.  The weight of the engine is in the very front of the car, and the rear wheels push the car forward.  This works similar to a shopping cart or bicycle, you are providing power to the back, and the front wheels are doing the turning.  Now-a-days you’ll usually only find this layout in luxury cars, sports cars, trucks, and SUVs.  Real wheel drive is great for power and straight line acceleration, but it’s not so great for control.  If you live in a snowy area, expect to only use these cars during the summer.

Image via Wheel Drive/Front Engine – Since the 1980s, this has became the default for most cars in America.  Like the FR layout described above, the engine here is in the very front of the car.  Unlike above, the front wheels are also doing the movement of the car and the back wheels are just along for the ride.  The advantages of this layout allows car makers to make smaller cars, and also provide vehicles that are easier to drive.  It’s much easier to control a wheel barrow by pulling it instead of pushing it, and that is the concept with front wheel drive.  The tradeoff is that there is significant “understeer” in a front wheel drive car, so it’s typically not as fun to drive.

Four Wheel Drive/Front Engine – This started to become an option on trucks and SUVs in the 70s.  The idea is that the more wheels that are turning, the less odds of you getting stuck.  With four wheel drive, all four wheels are moving at the same effort to propel the car forward.  There is no intelligence, they just all go.  If you find an older model (pre-2000), you’ll probably need to physically lock the hubs to engage four wheel drive (the default is rear wheel drive).  This is still how most serious off-road vehicles work, but because of the locking-unlocking pain, it’s not so great if you are suddenly caught in a snowstorm.

All Wheel Drive/Front Engine – All wheel drive is very similar to four wheel drive, in that all four wheels are helping to propel the car.  The biggest difference is that a) it’s engaged at all times by default in most cars  b) the power distribution is handled by a computer.  This means that typically the car is using more power at the rear wheels, but a computer decides if a wheel is slipping, and redistributes the power to other wheels that have more grip.  This makes for a decidedly easier four wheel drive effort for consumers, with the only trade-off being control.  There is also a gas mileage tradeoff, because the four wheels are always working instead of just in the snow.

Rear Wheel Drive/Rear Engine – This is pretty rare.  The most famous consumer vehicle with this configuration is the original VW Beetle.  While the weight on top of the rear wheels helps some with getting stuck in the snow, having all of the vehicles weight in the back can cause for some interesting driving.  The Porsche 911 is another really famous vehicle with this configuration, and it’s notoriously easy to lose control with it.

Rear Wheel Drive/Mid Engine – This is almost always found only in sports cars, where the aim is a perfect 50/50 weight distribution.  This makes these cars some of the best handling on the market, however there is a big trade-off that the engine is usually sitting literally right behind the drivers head.  Mid engine cars typically have much less cargo room than other cars.

What’s your favorite configuration?  Let us know on Twitter.