Sometimes you simply leave your car for service, and instead of getting it back fixed, you don't even get to see it at all, because it burned completely, until nothing has been left from it. This Tuesday night at this Chevrolet dealership, shortly after 7 p.m. a janitor was cleaning in the service building at Buff Whelan Chevrolet in Sterling Heights, Mich., and spilled cleaning supplies, causing what the fire chief called a "big ball of flame to erupt." About 30 vehicles were destroyed in a blaze. No one was reported injured, fire officials said. The cost of the damage was unknown. About 15 vehicles in the service building and 15 more outside were charred by the flames, said Sterling Heights Fire Chief Chris Martin. When the fire crews arrived, they "realized they had a big problem on their hands," Martin said. "The roof came down. The walls came down.". Martin called for a fourth alarm after arriving at the scene, which summoned every community in Macomb County north of Detroit to help control the fire.