Leaving a vehicle at speeds less than 10 mph is an Easy  AGI check. Above 10 mph, it becomes a bit more difficult (Challenging .) At 25 mph, and each 25 mph increment thereafter, the difficulty increases one level (10 mph=, 25 mph=, 50 mph=, etc.)
As for damage, a 10 feet fall equates to hitting the ground at a bit over 17 mph. Round that to 20 mph and call that 1d6 damage, with +1d6 for each additional 20 mph. That's 1d6 unsoakable damage for each SPEED 2 the vehicle is travelling if the AGI check misses. I think even a successful AGI check should still take a point of damage for each d6 of damage that would have been rolled had the check failed.
(Though, realistically, leaping from a vehicle travelling 60 mph would be the equivalent of falling 120 feet.)