As I tend to cache a lot in the city, my trusty Gemini Panelvan. Cheap enough for a uni student to own, brilliant fuel consumption around town, small enough to park unobtrusively in random places.
For the caches with harder tracks I occasionaly have to actually borrow my Dad's old Jeep Cherokee. However, that said I can get my Gemini into some off places (and get her out again )