Ever wondered why some cars have their front wheels driven, while others are driven by their rear wheels?
It used to be that almost all cars, with the exception of odd-ones-out like Citroen, DKW and Saab, used rear-wheel drive (RWD) but then almost half a century ago, the Mini came along with front-wheel drive (FWD) and turned the automotive world on its head.
The Mini, (facing page) with its engine turned sideways, used FWD as part of its brilliant packaging.
It eliminated the conventional driveshaft from the gearbox to the differential, saving some money, and allowed more interior space as there was no big driveline hump.
Weight savings were possible because the gearbox and differential were located in one housing.
FWD also lost less power through mechanical inefficiency. And with engine weight directly over the driven wheels, traction was improved on slippery, snowy or muddy roads.
It wasn’t long before manufacturers worldwide embraced the idea of driving the front wheels.
At first, it became the favoured configuration for small cars, but nowadays, FWD can be found in most sizes, although it’s common for large cars to still be driven by the rear wheels – the Aussie Falcon (above) and Commodore are cases in point.
So why haven’t all cars gone FWD if it’s such a great configuration? Unfortunately, there are disadvantages; and there are also points of view. The controversy has gone on for decades about which one is the better configuration.
Manufacturers of large and powerful cars have tended to stay with rear-drive partly because of front-wheel drive’s excessive understeer, a potentially undesirable handling characteristic.
Understeer is the tendency to turn less sharply than the driver intended and is present, to some degree, on all FWD cars.
There has also been the issue of stress and component wear on larger, more powerful FWD models – a characteristic well-known to owners of the first popular big FWD car, the Oldsmobile Toronado (facing page) introduced in 1966.
With more weight over the front of a FWD car, the back end tends to become light, especially during acceleration.
Ideal weight distribution for a car is often said to be 50-50 front and rear, but FWD cars rarely get close. (Neither, for that matter, do many of the nose-heavy RWD cars.)
There’s a saying among experienced and enthusiastic FWD drivers, “put the gas to the floor and steer; the rear will follow”.
Indeed, the hard-worked front tyres must transfer all acceleration, steering, cornering, and most braking to the road. The rear set has little load and is more or less along for the ride. That’s why you’ll often notice front tyres wearing significantly faster.
On a RWD car, the two rear wheels take care of acceleration, leaving the front pair to do the steering and most of the braking.
A skilled driver can “steer” a RWD car with the accelerator by applying power and sliding the rear end while in a corner, which is why the configuration is often favoured for sports cars.
Meanwhile, today’s electronic traction control (ETC) has tamed one of RWD’s worst habits – the rear end breaking traction on wet or loose surfaces, a trait well-known to drivers of powerful Aussie utes with no load in the back. ETC has closed or even eliminated the traction advantage of FWD.
Advances in tyre design have helped, too.
The success of traction control may well spark a renaissance in RWD cars, which have a mana among some drivers because the configuration has continued to be favoured by such prestige manufacturers as BMW and Mercedes-Benz, and is the favoured sports car layout.
The original Volkswagen Beetle and current Porsche 911 families are prime examples of the other RWD configuration, where the engine is mounted in the back, driving the rear wheels. This has some of the advantages and disadvantages of FWD, only the other way around!
An advantage is that the front wheels are free for steering and braking. Oversteer, when the car turns further than the driver intended, is a main characteristic and driving experts tend to agree that understeer is safer for the average driver.
FWD and RWD layouts are based on using only half of a vehicle’s wheels to deliver power to the ground. So if those other wheels are just sitting there, why not use them too?
The concept of all-wheel drive is not new. The Dutch manufacturer Spyker had such a vehicle on display at the Paris Motor Show back in 1903, but it was to take many years before it became popular on road cars. It’s a topic for a future Auto Adviser column.