First, I would use a steam cleaner to remove coarse dirt, and then a degreaser, or gasoline, you can. I also use a car steam cleaner according to the instructions https://www.fortador-usa.com/blog/car-steam-cleaning-process-what-is-car-steam-clean to clean the whole car the steam is very efficient and safe working with it, and steam cleaners are easy to use and reliable. Also save on the use of chemicals.