I know of a few 172 & 172 turbo conversions in 5's (as well as a VAG 1.8t), alot of work involved & i'm sure the bonnet has to be raised or have a bulge fitted to clear it, not sure if the 182 is any larger than the 172 or not.
Join the RTOC if you want info on these conversions, i'm afraid you will need to join by paying a fee though.
ATB
Steve