First, congragulations on being a newbie that actually correctly referred to the car as a bimmer, most get it wrong and call it a beamer (motorcycle).

In years past it was not a good deal to lease used vehicles because they would set the residual values very low and have poor money factors. Maybe it has improved, but I doubt it. On new leases, the depreciation is easier to figure out.

Even if you purchase a CPO car, you are still going to have to pay for service and some items (like tires, wipers, and other items) that are not covered by the CPO warranty. Figure $100 a month.

If you want to do something close to leasing with a used X5, just buy with a 100% 6 year loan. After 3 years, the car will be worth about half as much and the loan will be about half paid off. You can then sell the car for approximately the loan amount while having minimized your out of pocket cash and cash flow during ownership.

Do not buy a toureg, they have been a nightmare in reliability (see consumer reports) and they depreciate like mad. If you want a small to medium SUV that holds its value well outside the X5, check out the Lexus RX 300 and 330.