First of all, will the S5 be in the same price range as the current M6 coupe? Second, which do you recommend? I'm really big on performance and interior quality + ergonomics.

m6~! its faster and nicer the audi is a regular car but the m6 u never see it and its super fast also i like boobies

Well I think the A5 would rather compare to the BMW M3. And I prefer the M3, I think the A5 is a front wheel drive, while the S5 is of course a quattro. A rear wheel drive is more fun to drive, so M3 is better. If you can afford the M6 go ahead, it is a dream car which can easily compare with Audi R8. Quality and performance are quite equivalent in Audis and BMWs.

Get the M6 its an amazing car, just about everything you could possibly want in a sports car/sedan oh yeah...... they will go over 200mph!

I would go with the M6. It looks alot better than any other car in it's class.

The M6 is a very impressive car but fugly IMO

No disputing the presence the M6 has on the road but there are nicer looking ways to get around.

Flattered again that the S5 is being compared to BMW 6 series.