IMO, if you have $15000 and want to buy a car you should probably get a new ford fiesta and drive it for 10 years. If you spend the $15000 on a 10 year old X5, you will not be able to afford the inevitable repairs.

However, if you have $35K to spend, I think you are better off financially buying a nice used X5 and use the $20K to keep it nice (especially if you want a SAV).

I may be out of touch, but to me, there aren't any compelling new cars / trucks/SUV's that cost less than $30K. And even a lot of those cars don't have the features of a $15000 X5.