The main reason I went for the 184 over the 150 is that there noticeably more power and torque, especially when coming out of corners and I was already used to the power and torque of the 170 and didn't really want to go backwards. As far as the S3 is concerned it is a nice car but although I have owned many different petrol engined cars including four A3s, a Golf VR6 and four Golf GTIs I find I now prefer the low-down power and torque of a diesel. Also the S3 comes with 'extras' that I would definitely not want on my car, like sport suspension, 18" wheels, leather upholstery and flat-bottomed steering wheel. So I went for the 184 TDI in Sport trim with the softer SE suspension and as Audi only do the 184 with s-tronic in quattro form I had to have that as well (shame!) I'm certainly no 'boy-racer' but I still like to drive in a lively manner and find the 184, s-tronic, and quattro and SE suspension suits me very well. But a lot can depend on what you have been used to in the past. I'm sure if I was still driving my original diesel A3 the the current 150 would appear more than adequate.