in the .sco file of the object you want to become a petrol station you can add [nocollision] (so the bus doesn't collide with the object) and [petrolstation] so the object acts like a petrol station when the bus is placed in/over it.
View attachment 67979
.sco file example (adapting the single garage)
View attachment 67980
success: garage object now acts like a petrol station
Because the bus has to be 'in' the petrol station for the option to be available, I think you'd be best off using some sort of invisible box with no collisions as the actual petrol station/charging facility while leaving the visible charging equipment as a dummy object with no function.
That way you can pull up beside your visible charging station to use it instead of having to run it over or clip through it.