So technically, they are really offering you in the ballpark of $43k for the 335. Sounds fair, but always negotiate the deal before talking about trade-ins. I've also heard of people getting their cars for the same price without trade in. They are in for making money, and making money they will be doing if you go ahead with the deal. It depends on what packages you're getting though. If you can get them a couple grand more off, you're in safe territory.
2015 BMW M3 (ED 03-11-14) /l\ Austin Yellow /i\ 6MT /l\ Exec Pkg /i\ HK Audio /l\ 437MCCA Member