It's a 1949 MG TC.
"Shelby drove it to back-to-back wins in races in Oklahoma in 1952, after borrowing it from a friend. It has a 1,250-cc, four-cylinder engine and can hit a top speed of about 100 mph."
http://www.autoweek.com/apps/pbcs.dl...FREE/810099978
My dad had an MG TC when I was kid. Great looking car, but my dad always said that it drove more like a small tractor.
