I heard Confidential Witness (CW) on WABC radio a few months ago. He stated that when he saw Foster, he originally thought the man was sleeping. It was only upon closer inspection that CW realized Foster wasn't in any condition to wake up ever again. This sounds more like Foster was arranged, rather than he had just shot himself.
Of course, a man who takes the trouble to shoot himself without leaving prints on the gun (perhaps by holding it in an oven mitt, which then winds up in his glove compartment), can control his body movements while expiring.