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Discussion in 'New A3/S3 (8V Chassis)' started by Itguy, Apr 14, 2014.
Jeez, the Golf is sure getting some free publicity here..
That may be, but It's not very positive publicity.
So, correct me if I am wrong...
A FWD car with 280ps is as fast a 4WD car with 300ps. Why?
Could it be the 85kg weight difference?
People keep saying that the 4WD would make all the difference in the wet. Why?
Surely the lighter car would have the advantage under braking and mid corner - even in the wet.
I have watched a fair few youtube videos of Audi vs BMW in the wet. Why does the Quattro appear to make so little difference in the wet?
The only advantage the 4WD would have would be traction out of slow bends for a short period? How much use is that in the real world?
I remember watching Top Gear comparing 2 500bhp cars. Clarkson said one car was faster because it was 100kg lighter.
Example, 2 identical cars both 300 engine bhp, one FWD one 4wd. You lose power through the transmission before it reaches the wheels, with 4wd you have extra transmission parts to power so get a bigger mechanic loss than FWD... so FWD maybe 280 bhp at the wheels whereas the 4wd car maybe 260bhp at the wheels.. also the extra mechanicals needed to drive 4 wheels adds extra weight which makes the car slower in turn as the power to weight is reduced
Most of the benefit in the wet is off the line or when accelerating up through the lower gears (out of corners) in the wet (with Haldex/Quattro). The 2 wheel drive variant will then be marginally quicker once traction no longer becomes an issue (down to weight and drive train losses of 4wd).
Modern traction control systems and improved tyre compounds / tread patterns have helped RWD cars close the gap, but they are still far more likely to bite at the limit.
For the average driver that just wants to go quickly in any condition 4wd is a useful way of cracking the nut as you don't have to employ a significant step change in driving style. Most people don't have the skills to drive a FWD or RWD car that fast / safely in the wet, and as you well know we get an average of 190 days rain in the UK every year (it just feels like more).
A FWD car will have traction issues, and without a decent LSD will waste some power at various points of accelarating and turning in. Off the line, and from low speeds, you'll get torque steer fighting you for the wheel as the torque from the engine through the driven wheels also impacts the steering. As you push around a corner you'll get understeer with no real route to correct short of slowing down or maybe a little trail-braking (unless you have an LSD). With 4WD you eliminate torque steer, and add an option mid-corner as it will shuffle torque to the rear to counter it. Yes it will add a bit of weight, and on certain tracks, in certain conditions, 4WD won't offer a ton more, but in less than perfect conditions, or on tracks with lots of twisties, and low speed corners where you can maximise grip it will offer a lot vs FWD. Vs RWD is a different matter...
Not really. The track is a million miles from real fast road driving. The 4wd wins every time in the real world. My friend has an m3 and we were racing an rs4 on some Northumberland B roads. He just couldn't keep up with the Audi as rwd may excel on the track but in the real world if his back end went we'd be in a hedge. Yes I know the seat is fwd but the point don't judge a car just on what it does around a track it might be on 0.5% of it's life!
One big difference in road vs track driving is you can push much harder on a track. If you lose the back end on a track you have more space to correct and often grass or a gravel trap to spin into, on the road that's likely to be oncoming traffic or a ditch. Another thing is that on the road you spend more time at low speeds where 4wd traction makes a difference.
Unfortunatey, the part of the UK we live in has well above average rain fall
I'm just playing devils advocate. I know the advantages of 4WD. I just like to weigh up all the pros and cons.
The Quattro reduces the boot size to much to be practical for my work and it would also be hard to justify the increased fuel consumption for the number of miles I do. The 184ps FWD A3 should be just as good for overtaking between 40-70mph. I doubt if Quattro would be much help with that amount of power at those speeds.
I've had wheel spin in 3rd gear (and regularly in 2nd) in heavy rain at full throttle in my FWD 200HP Scirocco, so I do still think stability is an issue with reasonable power in a 2WD car in adverse conditions
Someone I work with had an Astra VXR and was getting wheel spin in 4th if he booted it, FWD really doesn't work that well over 200 bhp.
Might be of interest to note that the fastest M3 lap of the Nurburgring is 7.48. Whilst the fastest RS4 lap is 8.09
but did you note the two posts below? The Nurburgring doesn't have any bearing on real world (i.e: road) driving! Hit one single, solitary pothole mid-bend whilst ragging it & the M3 becomes a hedge seeking missile, M3 owners know this, so they won't push it too much on roads.