Mr Horsepower the iconic hotrod brand of Clay Smith Cams. Vintage signs decals and hot rod signs. Mr. Horsepower is the cartoon mascot and logo of Clay Smith Cams, an auto shop established in 1931. He is a sneering, cigar-smoking bird with red feathers and a yellow beak. The image is a caricature of legendary hot rod guru Clay Smith (1921-1954), well known for his red hair.