[mlyle]

A. If the car needs cleaning acutely because of a mess, it can go to the centralized location, and top up charge a bit in the process.

B. If the car is reaching the point it needs cleaning without an acute mess, it can go to the centralized location next time it needs a charge.

C. They can also elect to have people at the charging centers at off-hours to clean a subset of cars, to reduce the amount of B you need to do.