I have been telling my kids this story for years. It came on TV (most likely ABC, NBC, or CBS) in the 1970s around Halloween time.
The plot line was about a kid who comes back from college and decides to spend the summer on a project. He goes to buy an old car that had gotten hit by a train in the 1910s because at that time it was the thrilling thing for kids to race trains and try to cross the train tracks ahead of the train without getting hit. Sadly the couple in the car didn't make it. So the boy buys the car and spends the summer restoring it to pristine condition. He decides to take the old road into town instead of the new highway. As he's driving he keeps passing other vintage cars from the 1910s. When he gets to town he is completely amazed to see everything is from the early 1900s - including the people dressed in authentic clothing, the shops, the cars, etc. He gets out of his car and starts to walk around, looking in shop windows and marveling at the sights. Then he looks back at his car and sees someone starting to drive off in it. He runs after it and gets in front of it. The car stops briefly, horn blaring, and then they start up again and drive around him. The kid walks home, his new car having just been stolen.
Fast forward to the present. It's been about a year. He has a fiancee. He's over at her grandparents' house having brunch. He talks with the grandfather how he loves old cars and he had restored one but it had been stolen. The grandfather says tells him he has a surprise. The go to the barn and take a tarp off a car that is stored in the barn. It's the car the boy had restored - but in perfect condition. He asks the grandfather about it and the grandfather tells the story of having driven with his wife and almost got them killed by trying to race a train and cross in front of it. But at the last moment he realized he couldn't quite make it so he veered away. Apparently that moment of delay that the boy had caused him that night was the difference between "going for it" and getting killed and deciding he couldn't make it, living, having kids, and having a granddaughter who is now his fiance.
Does anyone else remember this? Do you know what this was called, when it aired and on what network? Did it come from an existing science fiction story that I might find so I could read the original?