Well, we have to remember that there's been a war going on ever since Michael killed Sollozzo and fled to Sicily. This car...and whomever was in it...could've been one of the casualties.

Tom is not about to go into detail with Kay everything that's been going on, so the simplest, most logical reply would be just the one he gave her and then quickly get her off the subject.

Also, it could very well have been an accident where nobody got hurt. Maybe Sandra was again demonstrating her husband's size to a friend and took her hands off the wheel for a second too many. Could be anything we want to imagine. Personally, I always found it a nice side touch but not really relevant to the overall story.

Maybe someone who's read the book can add whether there's an actual incident involved with the car.

Apple