Don't trust them!.
Don't believe them! I took my car in to have the oil changed and I KNEW that they would hit me up for the usual - fuel system cleaner (which although they claim, is NOT recommended by manufacturer as they state) and automatic transmission flush. It was about time for a transmission flush so I did my due diligence the week before and found that my car manufacturer required a specific transmission fluid. So, I called Mister Car Wash to verify that they did have this fluid. They said they did. When I arrived, I stated I wanted the transmission flush if the had the correct fluid (which I told them the name of). They checked and came into the office to tell me they did have this fluid (they confirmed the specific name). I asked them to do the transmission flush since they stated they had the fluid my car's manufacture required. When I picked up my car I confirmed that they completed the flush with the fluid I requested. It was at this point, AFTER my transmission fluid had already been drained and replaced, that they started tap dancing around about using a comparable fluid. What??? I asked THREE different times if they had a specific fluid BY NAME, not brand. After wasting 10 minutes of my life explaining to me that it is comparable, blah, blah, blah...I realized I was stuck with something in my car that I didn't want. Thanks for nothing Mister Car Wash. Justin, Jeff and their staff let me down.
I knew you had to watch these guys since they always recommend services you don't need. They pray on the uniformed. Little did I know they would flat out lie. I did everything I could to know exactly what my car needed. Despite this, they still got me. Don't trust them with your car or money. They only care about one of them and it's not your car.
On to the car wash...if you must, use them for basic washes only. Don't use the detail services. I've previously had the full exterior and interior detail including exterior wax. The wax left my car with swirl marks and the interior chemicals shine the interior of your car (leather, dash, plastic, vinyl, etc.) so much they look so cheap you'll wish you never let them touch your car. I no longer use them for detailing and only run my car through the express wash if absolutely necessary.