Chemicals alone cannot clean what equipment cannot reach. The areas of concern to all operators should be fronts and rears of vehicles as well as the windshield (especially the area between the lip of the hood and the other side of the wiper blades. If you leave a mask on the windshields, customers will not be happy and it will ask them to call into question the quality of the rest of the wash. Wheels are especially troublesome due to brakedust. Here you need not only a great wheel cleaner but a high pressure unit that will completely cover the wheel and pivot as the wheel passes which increases both coverage as well as cleaning time.
The formula is simple - Clean - Dry - Shiny cars. Anyhting less and you will be in trouble.
Owning and operating a tunnel is far different than operating an in-bay. First customers expect and demand) far more quality than from an in-bay. Secondly, you have attendants for them to complain to, in-bay's do not. Lastly, the customer will expect you to take care of extra-ordinary cleaning problems that they come in with (snow, ice, mud, bugs, bird droppings,etc.). Faill to do that and you will have disgruntled customers regardless of what you charge.
Lastly, do you really think that free vacuums are going to generate more volume?
Bill