In the last ten years there has been alot of improvement by the car makers attempt in rust controll. I find that a good car wash with an underbody spray is a must do in a state like Michigan. This state uses alot of salt on the highways and I run my truck throught the wash at least once a week. I am also a firm believer in a quality paste wax job 3 or 4 times a year. My truck is just short of 4 years on the road and has zero rust.