Ok, here are a few thoughts on how I might do it.
Old Beetle(Herbie works great), Fiat Abarth, 2CV, etc are good as those cars got personality IMHO.
First strip off/damage a fender or two, rip the engine hood off and/or damage it the borg gear has to get in there in order to take the car over.
Replace one of the headlights with a Borg Eye or similar preferably the side where the fender is missing or "damaged".
Sits we need no stinking seats no more, put some hardware/weaponry in there.
Just some random thoughts that popped into my mind.