put yourself on google places and yelp (if you haven't already). try and get some of your existing clients to take the time to leave you a positive review. may take some incentive for them (free wash maybe?) but the positive online reviews hold weight with people. I've only gotten a few people to actually post on there for myself but it has made a difference
just be careful on yelp. they can 'filter' the reviews. meaning they're still available, just not really obvious where you have to click another link and fill out a text box to read them. I do not understand the criteria by which they filter the reviews but the intention is to prevent phoney reviews