There's also A Deadly state of Mind. The fake story doesn't cut it because the made up killers would've been seen pulling up at night along the driveway. But alas it doesn't match your scenario either.

Cars! The episode that comes to mind is the one about the aging actress who lives in the studio and kills her assistant. She burns one car and then tries to kill the columnist by running him down.

The only other accident I recall is in Publish or Perish when the Cassidy character acts drunk and hits the couples car.

I don't recall any Columbo episode that matches the one you describe BUT I remember seeing a different tv show episode that resembles that. I just cannot recall the details.