You should probably drive, but it depends on why you are going there! Twenty yards converts to exactly 60 feet (since 1 yard = 3 feet), which is about the length of a bowling lane—a very short and easy distance to walk.
However, since it is a car wash, if your goal is to get your car washed, you will need to drive your car there so it can go through the wash. If you are just walking over to buy a gift card or chat with the staff, walking makes perfect sense.
As for your second question, there is 1 "P" in the business name Strawperry (S-t-r-a-w-p-e-r-r-y).