I always recommend a complete break with the old wash if there is a problem with the reputation of the business.
This means stuff like creating a new business name and buying new highway sign inserts, changing the image of the wash (i.e. new color scheme, new carwash reciepes, brand services, etc.), upgrade the lighting, pressure clean the wash-bay (paint if necessary), overhaul the equipment (if necessary), upgrade the POS (if necessary) to one that has network
marketing capabilities, add surveillance cameras, place some temporary yard signs announcing "under new ownership," re-surface the pad site and fresh line painting (if necessary), freshen up or add some landscaping and host of other things that transforms the old into the new.
Then hit consumers with a wave of
marketing and promotion. For example, direct mail (Moving Targets), several press releases to local radio and TV stations, Internet website, hosting some charitable events, etc.
When you reopen, spend some time on site (several weeks to a couple of months) and baby-sit the wash to show customers you mean business with the turnaround.