It's your money and you will do with it as you please. There is a lot of mixed opinions from everyone about what your decision should be, but I don't feel we have enough understanding of why you are wanting a new car and are considering the challenger. My question is what will be the purpose of the new car you choose? If you're just looking for a direct replacement to whatever you feel you get from your 335i, I doubt you will find it in the challenger. If you're wanting a muscle car you're in the wrong year. You need to go back about 45 years.
My personal opinion, if I was in the situation to purchase a new car and wanted a muscle car, would be to purchase a late 60's early 70's muscle car. I would keep my current vehicle as a daily, or maybe in your case sell the 335i for an economical vehicle ie. accord, focus, etc... and have the muscle car in my garage to work on and drive on sunny days.
Just my $.02
