I just came back from the Detroit auto show. I was asking the same questions you are. I think after seeing both cars I would lean towards the 335. With just a 200 pound difference in weight I don't think there is going to be much difference in performance. I was not happy with the reduced leg room in the back of the I135. If you do not want to take any passengers and want to drive the entry level 1 series then go for it. I think to say you have a sports sedan you need to be able to get a normal person in the back seat.