If you are able to look into the future, start teaching your child this difficult job now. In good weather, go out of town together and wash your car there. Explain to your child how to do this. Give him some easy task: let him seal the cracks on the wings and doors with a special compound, or use a mini-vacuum cleaner to clean the rugs on the floor.
Try to make this a pleasant and easy experience for your baby. Over time, try to develop the necessary skills and abilities in your child, and then, when he becomes a teenager, trust him with the work completely, unless you are used to always doing it together.