I honestly think you are pushing it a little bit looking for all of those qualities AND low 13s...maybe
high 13's would be more realistic. Anyway, an audi would be a good choice, but modding one to run low 13's might not be very practicle. I don't know anything about these cars, but I know other guys who have run high psi turbos on supras and what not, and you have to be constantly monitoring your engine and turbo.
Also, modded turbo engines have a tendancy to burn seals and just not last as long...
I'm not bashing the audi A4, as I don't know enough about them to do so, but I think what you really are looking for is an Audi RS6 or something, AWD, and reliable V8 power. I don't know how soon you are getting married, but many they will come down in price by then??