That's not true in all cases. I detail my car in the summer, but no time in the winter - it's too dark. The car wash I go to is superb. They use a foam lance first, then wash off, then spray on the shampoo which is rubbed with a lambswool mitt. Then rinsed off and dried with a hot blower. There is just too much water and soap being used for the mitt to get gritty. You will struggle to do better yourself unless you have the luxury of using the two bucket method.

Any minor scratches can easily be polished out in the summer.

Rick