BMWDees

I'm in the market for a new car and was looking at the 2012 X5 35D or 40D. budget is around $20-25K, mileage 100,000kms What the main things to look out for? How much are they to maintain? Should i look at something else? (keen on the 7 seater and sunroof) Do the sunroofs leak? What performance parts can you bolt onto these? Thanks