A few more things you may have either missed or been given poor information.
1. There is NO FULL SERVICE in the flex-serve paradigm; just hands-free carwashing and hands-on detailing. It's not a semantic thing because consumers already have a frame of reference about what full service is and isn't. Flex-serve separates hands-free (no labor) from hands-on (efficient humans cross-trained to perform manual stuff) from simple wiping down to a myriad of detailing services... so I grouped things that need a pair of hands and things that are done via automation. Studies show that consumers feel more comfortable having a detailer touch their car than the typical carwash attendant. So you have exterior (express) carwashing and everything else (detailing)... which is perceived as being "better, safer, more meticulous". Detailers simply are perceived as being "better".
2. As eluded to previously, having a real live service advisor engaging customers safeguards your business by having a knowledgeable personality setting the tone of the buying experience. Having several service advisors gives you great flexibility, and because they are also cross-trained, they can also load and detail. You will pay them more (bonus) but they are well worth the investment... and will pay for themselves while retaining your customers. Face it, too may operators place too little importance on hiring & retaining the right people, but those who do make more money and whine a heck of a lot less.
(continued)