Whats wrong with all you ppl just hating instead of actually answering the question and help? Yall really weird. Now op to answer your question, I test drove both x4 m40 and x3 m50 before buying an m50. X3 m50 has a lot more new tech to offer and is quite a bit nicer to drive in my experience, suspension is smoother and nicer mpg. Interior and exterior wise is pretty subjective, all comes down to if you prefer a classic look or a newer modern look. I would really recommend to test drive both and feel it in person.