The ONLY positive I could see in owning a 135i over a Z4 Coupe would be getting more options for aftermarket stuff for it. The Z4 is a little lacking in that field where I think the 135i will have tons of stuff available for it in the coming months... I can't even get a decent carbon fiber hood for my car, let alone other body parts !!! The 2 that are available are for a non-M Z4, and the other one is $5k and has fugly vents on it.
That said, the Z4M Coupe is still the drivers car...
hahaha
Congrats on the 135i tho, I saw a really tricked / raced out one on Saturday morning that sounded and looked badass !
You can't get wrapped up in resale on cars, no matter what you get, it'll be worth next to nothing in a few years. My last 2 cars were e-class benz's ( got the first one used, and the second one new ) and I lost my ASS on them. PLUS, they were no where NEAR as fun to drive as my Z4. If you're a true car enthusiast, get it because you love to drive it, not because of resale...
B