My wife is considering trading her '11 335d for a '13 GLK 250 Bluetec. She's looking for something with more utility (more golden retriever friendly) than her 3 series. I don't know much about the 2.1L engine and I didn't find much after doing a search. I want to know if there are any problems/pleasures that people have encountered with this model and year. Your feedback, as always, is greatly appreciated.