I have used the Waves one in Tesco car park
they seem to do a good job and worth it if the inside is a mess (I blame the grand kids!)
but only once or twice a year - and normally when it is cold out
I worry about using the car wash places elsewhere as I see a lot of things in the press about Police raids and finding all sorts of dodgy practices - such as modern slavery and stuff.
I presume - possible naively - that Tesco would not allow them to use their spaces if they were not sure they were clean (sorry!!)
but most of the time I just do it myself with a bucket, sponge and hosepipe