Coin-operated machines - add'l profit centers

As some of you know, in addition to operating a self serve and full serve tunnel, I also build and market a coin-op tire shine machine. I want to survey my fellow operators. Would there be a market for or any interest in the following coin operated machines to dispense:

- Foaming window cleaner. A towel vendor would have to be placed next to this machine also. The customer would buy the product and buy a towel. There would be two sales. Could there be a market for this ?
- Quick detail spray. A microfiber towel vendor would have to be located next to the machine. The customer would buy both the product and the the microfiber towel. Two sales for this too. Do you think this would sell ?

Thanks for any input.