This is a hard question to answer specifically without any knowledge of the business. What kind of car wash it is (auto, self-serve, or full service)?, How many bays does the car wash have? Is there any other streams of revenue? But in general I can give you an idea based on nationwide averages. For the purpose of this discussion we will focus on automatic and self-serve.
Automatic Car Wash Averages:
Average number of cars washed annually: 19,947
Average sale per vehicle: $6.34
Average profit per vehicle: $4.35
Average annual profit: $86,531
Average annual revenue: $139,000
Average Self Serve Statistics:
Average monthly revenue per bay: $1,489
Average percent of time bay is in use: 10%
Average annual revenue for a 2 bay operation: $41,000
As you can see there is money to be made in the car wash business
. You will have to do your due diligence when it comes to choosing a specific business as these are just industry averages, but you shouldn't have too much trouble finding car wash that will give you a healthy return on your investment.