In Minnesota, I suspect the roads are wet with salt and snow run-off most of the time during the winter. So if you drive the car regularly, washing it is a complete waste of time as the destructive salt spray has penetrated every joint and you are never going to wash it out…Now most cars have fender lips that catch and hold salt saturated wet sand. You might TRY to keep those areas cleaned out and avoid the classic rusted-out fender eyebrows…