Amongst various other cars, I did look seriously at the e90 shape M3 instead of an RS4
They're chalk and cheese in terms of driving style. The BMW makes you want to drive it like a hooligan to get the most out of it, whereas the RS4 is more gentlemanly if that's the right word
In the dry, the performance is comparible. However, stick a bit of damp in and the BMW driver won't see which way the RS4 went.
Very different sounding V8's too, but I prefer the sound of the RS
In practicality terms, the Audi wins hands down
Also, IMHO, less people will think you're a c0ck when driving an RS4 and it's less likely to attract rozzers / car crime too
Paddle shift in the BMW is really good, but you've got to make sure it's had all the updates or, as mentioned above, it'll run like a pile of pants
Get one with FBMWSH as the AUC warranty scheme (which is available on any uk car with FBMWSH) and significantly cheaper than audis equivalent (was circa £800/yr for <60k miles car IIRC)
Get the pay monthly warranty as that doesn't reset when car goes over 60k like the annual l/sum payment option does
Good cars though and fun to drive, but avoid red leather as although it may seem a good idea at the time, you'll soon realise its cr@p !
