I'm a fan of dual in bay autos, too. In my market, those customers are the cream.
Let me throw something at you: If you have to finance 25 years to make a carwash work, it's not worth it. Before you pay off that wash, you will have to reload those automatic bays twice, you'll never pay the place off; you're signing up for a lifetime of debt.
If you finance today 850K for twenty five years, you'll owe over 600K in the year 2017. It will be time for a autos & cashier reload, which will push your debt up to a million again on the entire property. You'll owe as much or more on it than when you opened it. fifteeen years from now in the year 2022, it'll be time for new SS & Vacs. In twenty years (2027), new autos& cashiers agin, which will likely push that total debt back up to your original financed amount twenty years prior.
In metro area, 25 years areas can boom or bust, What was once a vibrant retail area can be a shuttered warzone. Competition will come. And you're most vulnerable at the ten year mark when you could potentiall still owe a million on the property. In small towns all it takes is for walmart to relocate and they can gut the old area over time. Potentially, your wash will be a tired wash and someone, perhaps with the help of your distributor, will build another one in the newer section of town. After all, your distributor left your area alone for ten years. But now you owe more than ever on your wash.
My personal rule of thumb on a carwash is if I can't make the numbers work on a 15 year amoritization is to pass on the project. For that reason It's getting harder for new carwash projects to make financial sense to me.