It might be interesting to experiment with making abandoned vehicle more predictable. For example, maybe make it a 33% change for the vehicle to be abandoned when it has a damaged engine, 66% chance with a destroyed engine. These values are probably dramatically too high but I like the idea of making abandoned vehicles something a player could actually attempt to influence through at snares and mines. It also makes sense that a vehicle crew wouldn't want to remain in their vehicle once it looses engine power and comes under enemy fire.
Wow, this actually a superb idea..
I imagine people setting up ambushes with engineers behind the corner, waiting for tanks to drive over a couple of mines and having a chance to be abandoned. In this way, abandoning is a tactic you can use rather than an irritating feature.
It needs to be finetuned but I like it a lot.