Car Wash Insurance

I have a prospect that has a hand car wash not a self serve carwash. He is also been awarded a contract to pick up cars from a local high rise apt building and will begin picking up autos and bringing them to the car wash which is less than 2 miles away washing them then returning the cars the apt building.

Question is in the event of an auto claim let's say he wrecks a customers car while he is driving the car to the car wash. Will the garage keepers insurance pay for the claim or will the non owned auto insurance pay for the claim? Or am I completely incorrect??

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