一路飚车的“闪电”却在途中意外迷路，闯入了66号公路旁一个貌不惊人的陌生小镇，横冲直撞的他毁了镇民不少财产，为了尽快上路，“闪电”不得不答应做义工，和小镇居民打成一片。于是，他结识了很多不按规则办事的新朋友：直爽漂亮、2002年产的时髦保时捷 莎莉（Sally），有着神秘历史的1951年产老爷车 哈德森博士（
Successful rookie racer Lightning McQueen has, to his pleasure, just won a 3-way tie with elder rival Chick Hicks and champ "The King", but is also proud and unappreciative of long-time (mostly older) supporters enough to have his ignored pit-crew desert him. Accidentally lost en route to California for the tie-breaker, he crashes through Radiator Springs on Route 66, destroying the road and some property. Forced to remain in town until he repairs them, he's stuck in a small community whose tight-knit inhabitants accept neither his selfishness nor bad attitude. Refusing to respect them initially, he eventually returns the friendship of redneck Mater and falls in love with Sally, but can't seem to get gruff Doc Hudson, who keeps a painful secret, to change his mind about him. Soon Lightning learns the inhabitants of the town as a whole, who are almost a secret to the outside world, also had a past now painfully absent, and tries to help them enjoy it once more.