 I always change cars every two years. The difference is if I find a better model, I change, if not, just buy the same. I drove a BMW X5 V8, and it had problems. I changed to a Mercedes ML500, and had no problems, but it was not good offroad. Then I changed for a 2004 VW Touareg, it was more comfortable and user friendly. After 30,000 impecable miles, I traded it in for a 2005 Touareg in July 2005. With Pirellis on 18 inch wheels, it handles as if it was on smooth rails. Precise, totally satisfactory to drive, in both the city and highway. Then go off road, the BMW and the Mercedes had trouble in the Death Valley canyons, the Touareg makes everything steady and easy.