Well, just as a long-overdue update, I have about 5 more hours of playing time in on GTA IV.
I am playing on 360 btw, for those who are asking.
I am 100000% sure that the car blowing up was not due to any gunfire, hitting anything, or any other weird situations.
Case in point, it happened to me yet again, and once again, it was when I was driving a PMP600. Car parked on the side of the road, doors not even locked. I get in, start the car, drive off. About 10 seconds into me driving it, car blows itself up.
Seriously what the fuck