[vrighter]

I've thought about this further. You said it's even better if the vehicle can rapidly change from reverse to drive.

More generally, the bigger the acceleration in the forward direction, the better.

So the best solution is to reverse and crash into a wall. It would bring your speed to 0 almost instantly. Meaning the acceleration would depend on how big your inertia is, not how powerful your brakes are (and the limits of your tyres' traction).

[BugsJustFindMe]

Well yes, obviously, but then we need to balance the cost of closing the door against the cost of repairing the car. And also what if there isn't a convenient wall nearby? :)

[vrighter]

eh... they're insured. If lacking a convenient wall, the car behind them will do almost as well