Just been reading your latest on . My mantra on Stats is that they must do one of two things:
1. Make interesting tactical decisions.
2. Track the state.
Given that, I would include the following from the list:
HP. Vehicle takes damage in exactly the same way that humans. They have more boxes. I would recommend four speeds: Top Gear, Running, Crawl, Immobile. Top Gear means that you can go as fast as you like. Running is the pace at which humans can keep up. Crawl is good for long distances but forget losing anyone and immobile is important because the vehicle may still remain useful even when it can't move. Once you've run out of points then it should be useless.
SDI So the GM knows what dice to use when rolling damage dice (funny that you missed that!).
Abuse. As you say but I would say that it drops a dice only when they fail a roll or they do something fabulously stupid. Like running at full speed over a home-made stinger.
Fuel Yes. Yes. Yes!
Agility - for all driving rolls, we're using Technique. Agility would be good as a +d6s added to this roll. Nice and simple. A difficult to drive vehicle would have no bonus (in our game, a box-van turned APC) a well maintained pickup +1 (in our game they have a pickup truck).
Bonuses to weapons / skills - good for specialist vehicles. Nice.
Ones I'd ignore:
Speed - so very difficult to judge the speed of something because of the terrain and abandoned vehicles all over the place. Most vehicles get modified by the scavengers (normally to lose speed), so this one is a bit moot. Really, a player will decide on one of four speeds: flat out, fuel economy, cautious or stopped. The speed their going at really sets the difficulty level when doing driving rolls.
Crew and passenger capacity - I've seen 8 people get into a car meant for 4. This is a bit moot. PCs will hang onto the outside. If there are descriptions of how big something is and what type it is, that should be enough. The PCs should be encouraged to modify the vehicle (tear the roof off) and a capacity stat suggests a limit. I'd rather leave that as a common sense ruling. Some for Strength/Towing capacity - I think it's a step too far.
Wits / Initiative modifiers - Starting to feel a bit kitchen-sinky.
HP thresholds - This should really be part of HP at the top.