I personally don't see the point. It's not like you're going from the X to an M3 where you'd get a significant performance advantage. You're going to lose the superior seating position as well as whatever utility the X5 has. I'd imagine that you'd be paying at least 5-10k extra to get into the 5 as well. IMO, the bottom line is that I don't see what you're going to gain by going to the 5. Goodluck with the decision .