Who are your nearest competitors and what do they offer? What do you do that's better or different? You have to have a USP. Describe your ideal customer and work out where they are and when to contact them (e.g. are they on social media, in a workplace (lunchtime service while people work?) etc). Sorry I don't know anything about your industry but imagine it is competitive so you'll have to work hard to get people to come to you rather than the cheapy hand car wash I'd imagine.
Best of luck.