It's way too easy to get AI to abandon vehicles in this game and it removes the challenge of going up against any of the vehicles.

All you need to take out a wheeled IFV is a machine gun, or a single RPG for a tank... a mobility kill -always- makes the AI jump out of the vehicle, even if there is no other damage at all, in the middle of a firefight, which makes no sense.

The only vehicle that the current system makes sense for is unarmored trucks, which offer no combat ability or protection.

MRAPs should only be abandoned by back-seat passengers, and perhaps the driver (the windshield is pretty exposed, who can blame him for leaving?).
The gunner should stay in the vehicle and provide fire support unless the vehicle is compromised entirely, out of ammo, or the threat of combat is over.

True armored vehicles, the entire non-passenger crew should remain in the vehicle and fight until the vehicle is incapable of shooting back due to ammo exhaustion or battle damage, on the verge of complete destruction, or combat is over.

Furthermore, it would be much preferred if AI would perhaps stay in their vehicles post-combat and wait for repair support to arrive on-site and get them rolling again, given that such options are available at that moment.

These changes would make fighting AI in vehicles actually dangerous and put a lot more risk behind even engaging a simple MRAP head-on without proper preparation, and result in a lot less ridiculously easily acquired 'op-for' equipment.