Mr. Horsepower is the cartoon mascot and logo of Clay Smith Cams , an auto shop established in 1931. The woodpecker was a characterization of the owner, Clay Smith, as a "red-headed, cigar-smoking, fun-loving person." Mr. Horsepower is rarely without a cigar, but when he is, he has a "cigar replacement" - such as a candy cane for the holidays.
The Mr. Horsepower logo is commonly seen as a car decal or tattoo. The logo has also appeared in a wide range of movies, from the Coen brothers' Raising Arizona, where the main character, H.I., and his antithesis, Leonard Smalls, both had tattoos of Mr. Horsepower, to more recent films including Spider-Man and Gone in 60 Seconds. The Mr. Horsepower logo has appeared in video games as well, most prominently perhaps in Sega GT 2002 for the Xbox video game console.
Eddie's Auto Parts, based out of Knoxville, Tennessee, uses a logo almost exactly like Mr. Horsepower except that the bird has a rounded bottom to its beak, lacks a smoke trail from his cigar and has messier "head feathers." This bird logo can be seen on the famous Eddie's Auto Parts t-shirt. A blue version of this t-shirt being one which the stars of MTV's "Jackass" seem to share.
Mr. Horsepower is also often confused with the "Thrush Bird", the logo of Thrush, a muffler manufacturer. The differences lie in that the Thrush Bird does not have anything in his mouth whereas Mr. Horsepower has a cigar or a "cigar replacement." The Thrush Bird's beak is also curved on the bottom whereas Mr. Horsepower's is not. Both birds share a rather maniacal demeanor however.
To people in the mainstream, Mr. Horsepower is usually confused with cartoon character Woody Woodpecker. The notable points of contrast are that Woody Woodpecker's beak is curved but smooth on top and bottom, and his head-feathers form a well-contained "V" shape in early iterations or a sprout of sorts in newer iterations. The most obvious difference, however, remains in the portrayal of Mr. Horsepower, the Eddie's Auto Parts logo and the Thrush Bird as maniacal, whereas Woody the Woodpecker exhibits a more high-spirited insanity.
To add to the confusion, all four fictional birds are popular logos within the racing community - Woody Woodpecker being the most recent addition with its use by the Honda Motorcycle Racing Team.