Correct, an M3 isnt a tarted up 3 series. The engine couldnt be more different, it has a totally different layout, individual throttle bodies, .4L more and over 100Bhp more.
The suspension shares NO common components with the 3 series, the alignment is totally different, it has staggered wheels, much bigger brakes, a different steering rack, different exhaust, no traction control and a LSD.
I could spend all day listing the differences between a 911 C2/C4 and a GT3, and another day on GT3 vs GT3 RS.
So your A3 quattro sport vs S3.
Same engine, different turbo. So no extra displacement, but 35Bhp more. Suspension components are the same. Brakes - not sure, Golf anniversary had 312mm, wouldnt surprise me is the A3QS did also.
Steering & geometry - same. Exhaust - same.
So in essence, the vast majority of A3 - S3 changes on quattro cars was aesthetics only.
Makes it a tarted up A3 in my book, in comparison to other German manufacturers 'sports' models.
And these people who keep going on about high performance two wheel drive cars being troublesome in Britain are talking nonsense.
I'm running on road legal track tyres, on a stripped out, 4 million BHP RWD BMW, and I've only ever had a traction problem in the snow, or standing water.
And anyone on track tyres will see that same issue, 4WD or not.
It just looks like some people REALLY need to learn how to drive. And let me set the record straight, I'm not a brilliant driver by any stretch of the imagination but this 4WD is more usable, more of the time is nonsense.
Learn to drive.