I saw a movie in the early 70s, late night. It was an older movie in black and white. The scene recall best is of cars rounding a turn, seeing headlights racing toward them, then chickening out before the other “car” did, and crashing down a mountain..finally someone stays the course and it is learned it was a mirror across the road that caused it all….that is all I recall..It was kinda James Dean-ish..been trying to find it for 15 years!