I Forgot The Name Of The Movie Who knows it?!

I was watching it in school for fun and we never finished the movie so now i want to see it!. All i remember from it was an old movie and in the beggining it starts with a bum on the street and he tells a story about his past, and in that he lives with a black family and thinks hes black but hes white, then when he gets old enough he goes off on his own and hitchhikes until he finds a job at a car place, and then i left off at a part where robbers were trying to get free gas and tires and he tied there car to a pipe on the building!. And hes sorta a dumb guy!. Lol!. Yeah hope it helps!.!. But first person to tell me the name of the movie gets 10 points!!!Www@Enter-QA@Com

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