CONCORD, N.C.  – John Gray’s lime green 1970 Plymouth Barracuda was as good as gold in Sunday’s Pennzoil AutoFair presented by Advance Auto Parts at Charlotte Motor Speedway, earning Walt Hollifield Best of Show honors in a hotly contested showcase of colorful classic cars, hot rods and sports cars. Gray, a Ho-Ho-Kus, New Jersey, native, bought the car in…