Though by no means absolute, I think in some cases, depending upon the [hull] insurance on the aircraft, the aircraft insurance would pay for repairs to the aircraft, after all that's what it was insured for. But the insurer is certain to sue back the car owner and insurance. I just wonder what happens when you get the car owner to court, and they say that they were not driving it! - It's silly, but true! Now, if the same person owns the car and the plane, I'd bet that the insurer is going to laugh off both claims!