@Angela Doyle
A few things to consider
Type of wash- I’m guessing these are self serve with the spray want or in bay automatic where there are no employees needed.
Traffic flow-does the traffic flow and the businesses right near the wash support these incomes and any potential growth.
State of the equipment-is the equipment newer or older, is it well maintained?
Income over many years-weather plays a big part is the success of a wash, you want to see REAL numbers for st least 3, more like 5 or 7 years to get a better picture.
Sellers mindset-is he really selling 2 of 3. If he is getting older and wants to get out, you may be able to take over all 3 at the same time. You will get efficiencies of scale with chemicals and service calls.
Suppliers-talk to his chemical supplier and maintenance guy. These two people can make or break your car wash. They know everything about them and you will come in knowing next to nothing.
cash-is he reporting cash/coins from self serve bays and vacuum. If he is, great, you have s good picture. If he’s not, you should still do your numbers assuming there isn’t any other income. He can’t prove it and neither can you.
I’m sure there are more, but that’s a start. I’m glad to chat more if you would like!