What sort of mileage are you doing in it. If a low mileage get a big petrol - the values are comparitively low but they are so much better the diesel counterparts. Many can be LPG converted too.
V8 touaregs are silly cheap and very well engineered. Also I'm shocked you aren't considering discovery 3s - the best 4x4 on sale.
Car: 2010 Jaguar XFR (Stock - For now)
Gone but not forgotten: Highly Modified E90 335i LCI M Sport Manual (circa 480BHP/500lb ft)