Jafo666

Hi everyone this is my first post, I'm looking to buy an X5, couple of question i have: Should i go for the 3.0 or 4.4? Theres rumours about that the 4.4 has better MPG because the engine doesnt have to work as hard? But i dont think thats true, my current car averages about 21mpg so anything around that will be fine. Anything to check on the vehicle BEFORE handing over my money? What repairs are Common / Expensive? I see most are high mileage, is that a bad thing? Thanks!