Are FWD cars overall superior to RWD cars?

[Alberto Michelatti]

I am a FWD cars enthusiast, and I would like to explain why for me FWD cars are overall superior to RWD cars and, from a certain point of view, to AWD cars also.

1) the engine and the gearbox overall mass directly over the front axle means at the same time more brake power, more control, more directionality, more safety, more space, more stability, more traction.

2) the absence of the RWD longitudinal propeller shaft means at the same time less fuel consumption, less noise, less pollution, less space waste, less vibrations, less weight (up to about 100 kg).

3) with a FWD car, if you apply full throttle when cornering the car becomes understeering and the worst thing that can happen is that the car go straight, colliding longitudinally with the obstacles (take a scale car model and lock with adhesive tape the front wheels, make it run on the floor, and see what happens. Then lock the rear wheels and then all the wheels, and see what happens). Furthermore, on a FWD car generally only the wheel with less grip spins, while the other wheel keeps the directionality. With a RWD car, instead, the car become oversteering and the worst thing that can happen is that the car fishtails, colliding transversally with the obstacles. With an AWD car, instead, understeer and oversteer limits are obviously higher, but if you exceed them the car control recovery could be very problematic for a normal driver, because over a certain limit the car understeer with the front axle and oversteer with the rear axle, all at the same time.

4) a FWD car is very easy and instinctive to control, because if when cornering the FWD car becomes understeering you have just to release the accelerator pedal and, eventually, slightly adjust the trajectory. A RWD car is very difficult and not at all instinctive to control, because if when cornering the FWD car becomes oversteering you have to carefully keep pressed the accelerator pedal and quickly countersteer to keep the trajectory. The behaviour of an AWD car is generally quite similar to an FWD car, but when you exceed its high limits the control recovery could be problematic for a normal driver.

Briefly, I think that the overall best possible solution today available is a FWD car with an open differential, better if with TCS (Traction Control System: electronically controlled artificial limited slip differential actuated by brakes) and ASR (Anti-Slip Regulation: electronically controlled power modulation actuated by the drive-by-wire throttle). Why an open differential? Simple: just because with an open differential while one wheel spins the other wheel can keep the trajectory.

I think that the only real disadvantage of a FWD car is that it is not funny to drive, because the rear wheels are almost always perfectly on their ideal trajectory, short of you use some

like for example the handbrake 180° turn or the Scandinavian flick (pendulum turn). However, it is neither funny to bring your RWD car to a bodyshop for the reconstruction of the rear end, it isn't?

I think that the only two possible rational solutions are FWD or AWD; however, I think that a RWD car makes sense only in presence of huge power, rear engine and, most of all, in presence of very skilled drivers. I think that if you don't live in a territory with very slippery steepy roads, an AWD car is substantially useless... a waste, from a certain point of view. For example, I think that on a snow covered road it is safer to drive a FWD car with M+S tires rather than to drive an AWD car with normal tires.

And now, the curiosities corner.

Did you know what is the most powerful FWD car ever? As far as I know, the most powerful FWD car ever is the existing Pontiac Grand Prix GXP, equipped with a 303 hp SAE net 5.3 V8 engine (307 hp DIN, EU-spec).

They who say that the most powerful FWD cars ever are the 1966÷1970 Oldsmobile Toronado W-34 7.5 V8 (455 in³) and the 1970 Cadillac Eldorado 8.2 V8 (500 in³), both with 400 hp SAE gross (open exhausts, no accessories), are wrong, because when in 1972 there was the SAE gross to SAE net switch, the advertised power of the Cadillac Eldorado, for example, was of 365 hp SAE gross or 235 hp SAE net, while the power of the Oldsmobile Toronado fallen from 350 hp SAE gross to 250 hp SAE net (to convert DIN horsepower to SAE net, simply divide the DIN number by 1.0139).

For the ultimate, I think that the annoying and not dangerous FWD cars' torque steer issue, mainly noticeable on high torque FWD cars, is not depending by the half-shafts length, but instead it is depending by the overall torsional stiffness of the left-side half-shaft and of the right-side half-shaft, no matter if the equal length half-shafts or the unequal length half-shafts system is used. I think that when full torque is delivered by the differential to the half-shafts, the longer half-shaft, due to its weak torsional stiffness, accumulates a delay in torque delivery to the right-side wheel, and this phenomenon makes the car steer to the left-side.

FWD-FTW! Safety first!

Alberto.

[Leighcm]

Alberto...thanks for another great post!

I have a slightly opposing viewpoint to yours:

1.) I feel the rear wheel drive car provides far better handling than front wheel drive, especially around curves in the road. I prefer the rear wheel drive car for long trips, as less steering input is required on the long highway trips. A rear wheel drive car also feels more substantial to me.

2.) The front wheel drive has far too much torque steer, especially with the higher powered models, and it is much easier to launch a rear drive car in a straight line. Of course, the all wheel drive is the best, but there are so few of them available.

3.) Traction: I find that while it is more difficult to go into a skid in a front wheel drive car, it is much more difficult to pull out of that skid with a front drive....basically, if you lose it, you're done. In a rear wheel drive vehicle, while it is easier to slide or skid in poor traction areas, it is much, much easier to break out of that skid in the rear drive car. Take this from a voice of experience as I drove a 320hp Supra Turbo year 'round in Michigan (rain, snow, and sunshine). I had snow tires, traction control, a manual transmission, and limited slip, and I was good to go. I was the person who arrived early at work in my Supra, while others called in because they were "snowed-in" with their front wheel drive cars.

4.) Fun: the rear wheel drive is LOTS of fun...especially in the low traction areas. If you've never done it, "donuts" in the snow or on gravel are great! Crank the steering wheel, hit the accelerator, and slide around in circles. Also, it's much easier to slide around a corner in a rear wheel drive car, put the car into a drift, or parallel park using the hand brake to slide into place! You can do all this stuff in a front wheel drive car, but you have to be driving it backwards when you do it.

5.) AWD is not a complete waste in the fair weather areas. The rear wheel drive is great around curvy roads, but the AWD is the best. It's not all just for poor weather traction! There's also a lot less wheel spin in the AWD than in either the front wheel drive or rear wheel drive, and there is no torque steer, so launching the car is much better.