According to his aunt, Mrs. Steinmetz, Tennessee is a student of Oriental philosophy. That's how he learnt that things have an inner life, like wind, rain, traffic lights, can openers and little cars which is how he and Herbie became good friends.
He likes to tell stories about his trip to Tibet and is handy with a welding torch and creative, especially when he cuts up his "Edsel" and turned it into a sculpture. Even though he is Jim's friend, Jim sometimes does not take him seriously about his beliefs, especially when he does not believe that Herbie is alive until he witnesses him wreck his new Lamborghini.
Role in the film
Tennessee is the first person to believe Herbie is alive and befriends the little car and also gives him his name "Herbie" named after his Uncle Herb (It is not clear if Herb is Captain Steinmetz, Mrs. Steinmetz's late husband). He assists Jim on the racing circuit, cleaning Herbie and refuelling him.
He immediately shows a distrust towards Peter Thorndyke when he comes to the Firehouse to pay his respects to the little car. This makes him change his tune to Thorndyke and offers him a drink of Irish coffee. As they share a drink the two quickly get drunk and every time he goes off to make some more coffee, Thorndyke filled Herbie's tank with Irish coffee which will make him drunk during the next race. With Carole Bennet's help they manage to restore Herbie to health but is disgust to find out that Jim bought a new car and plans to sell Herbie to Thorndyke. When Herbie runs away, Tennessee refused to help Jim find him, since this was a private matter between him and the little car. After being charged by a Chinese gentlemen named Tang Wu, Tennessee manages to reason with him by speaking his language and showing Chinese courtesy.
He joins Carole and Jim in El Dorado and sits in the back seat with his welding equipment next to him. As they are near the finish Herbie begins to split apart and Tennesse tries to weld him back together while still moving. (Since Herbie beat himself up so badly when he ran away, he had to cut the frames to straighten it out and Tennessee was worried about his welding not lasting.) Eventually Herbie splits in two, but wins with his rear crossing the line first.
Tennessee is last seen with Tang saying goodbye to newly married Jim and Carole as they drive off on their honeymoon with Herbie.
In Herbie Rides Again, he is mentioned by Grandma Steinmentz, saying he had gone to Tibet to visit his ailing philosophy teacher.