[Corinthian]

I had a 08 335i coupe now a 08 535i

Most if not all systems, engine, electronics etc are the same so not much difference there.

The longer wheelbase of the 5er make it more comfortable and the bigger wheels/tires handle the crappy roads here in Chicago much better.

The sport package on the 5er is just right, on the 3er sport suspension is too stiff IMHO. Over the same imperfect local roads around here I find myself going faster with the 5er.