RWD faster than FWD/Matt Prior

franne,

From a technical perspective I cannot, but so far as I am aware there has never been a successful front-wheel drive F1 car and back in the days when BMW entered a factory team in the BTCC nothing else could touch them until the BMW's had some ballast added to allow the others to compete.

I believe this is down to weight transfer and mechanical grip. From a stand still under acceleration weight is transferred towards the rear of the car (ie the front lifts) the opposite is true for braking front dips. With a rear wheel drive car the weight is effectively transferred over the driving wheels producing more mechanical grip, with a FWD car grip levels are reduced as under acceleration there is less effective weight over the front wheels producing less grip. In general I believe this is the reason RWD generally show quicker 0-60 times against a FWD vehicle with a similiar engine, 30-50 or 30-70 is possibly a better measure to realistically compare a RWD with FWD with similar engine perfirmance.

I'd say that's correct. Having recently purchased by first rwd car I can easy feel the difference when pulling off briskly.

While driving my wife's fwd car a couple of weeks ago I had to accelerate quite quickly to turn into a junction because of heavy traffic (either that or sit there all day). I didn't exactly floor it but I was still slightly caught out by the amount of wheel scrabbling for grip and general lack of traction. If I'd done the same thing in my BMW there would have been no wheel spinning or drama in general, although 255 section rear tyres probably do help.

Watch how BMW touring cars pull away much quicker than the fwd opposition if you want to see it in action.

Okay if weather is good. However someone I know exchanged his BMW for an Audi because of difficulties experienced in icy conditions. He actually preferred the BMW but it proved impractical for his circumstances

It's down to the limits of the rubber.  Providing forward force requires grip, turning requires grip.  If your rear wheels push and your front wheels turn you have more grip available before a wheel loses traction than if the front wheels are having to push and turn at once.  It is not a massive advantage as obviously the rear wheels experience a lateral load as well, though not as much as the fronts but ultimately it is the second best solution to maximising the accelerating and turning forces after four wheel drive.  

Which Audi did he get? Not all Audi's give an advantage in icy conditions. One fitted with Quattro AWD certainly does, but in my experience, a FWD Audi is inferior to a RWD BMW even in snow and ice.

In any case, why didn't he get a BMW with xDrive? By all accounts it is pretty much as capable as quattro, and you don't have to go over to the Dark Side!

From personal experience in my opinion RWD is almost always inferior in snow and ice compared to a FWD due to having less weight over the driven wheels, a FWD in most cases has the engine over the driven wheels and this additional weight over the driven wheels provides more traction in very low grip conditions. I have found a couple of large paving slabs in the boot works wonders in the snow with RWD . Ultimately a proprer 4WD with the correct tyres for the conditions is the way to go.

That said alot of it comes down to grip. In snow the thinner the tyres generally the better as more force is exerted onto the road (its the old elephant and stiletto debate). This is where many cars fail in snow as with the trend for larger wheels actually reduces grip in the snow. With BMW's the trend for large wheels, run flats and RWD all work against grip in snow. Overall regardless of RWD or FWD winter tyres make a huge difference.  

We live on a steep hill and with the last couple of winters it has often looked like a car showroom of abandoned high end vehicles at times. The ones that always seem to have the most success are proper 4WD's and small FWD's.

An A3. I am just reporting, not commenting!!

By the way, the classic way to slow down on an icy road was gentle use of the handbrake. Can anyone say if electric parking brakes are of any use for this or are they just too "on or off" for the purpose?

Using the handbrake to slow down on an icy road seems like one of the worst things you could do.

I just use low gears to keep controlled going down icy hills. I wouldn't ever touch the handbrake to slow down.