Why would you care? If the customer wants the car coated and then decides to run it through a car wash, that's his business. After I am done with each detail, I explain how to wash the car, major mistakes to avoid, how to dry the car and I also explain why. From there, if the customer wants to use sand paper and green scotch brite pads to wash his car, that's on him.
As for doing Fire trucks, coating them would be pretty expensive. Depending what product you use, a typical coating bottle will do about 2 cars (CQuartz and Gloss coat for example). I don't know how much you would need but I can guesstimate about the equivalent of 6 cars on one fire truck... Ouch. McKee's 37 coating bottle is supposed to do about 10 cars. I have serious doubts about that. I have done 2 cars and 1 small SUV (For Escape) so far and the bottle seems very light to me now. Probably 1 or 2 cars's worth more in the bottle. Still, much more than other brands and the cost is much lower than other brands... so that would be my suggestion if you want to coat these trucks. 1 bottle per truck would probably do it.
As for price. I would charge them 10$ off per hour my regular rate (which is 40$/hour), for the huge amount of work that represents. Make sure to cover the cost of products and tools. You will probably go through at least 2 pads doing that much correction (maybe more) and a lot of compound and polish. Not to mention the cost of the coating itself.
If you do get the contract, please share pictures, that sounds like a lot of fun to do firetrucks. And hope there are not gonna be too many fire emergency while you are working.
One of the members on this forum is a fireman, maybe he has done work on a fire truck before and could give you pointers.
Good luck!
