I hate to tell you that John, but when it comes to sinister Citroën, the 2CV may not be the weapon of choice.
I mean this is the dream car of the average post-68 marxist student for life and vintage 68 student turned marketing director. In my opinion, they're more pathetic than sinister.
No, my advice would be to look into the Citroën DS for instance. De Gaulle had one as a president, and that was freakin' sinister -- although unlike Fantomas' one, de Gaulle's DS couldn't turn into a plane (though it almost turned into a coffin once, thank to the OAS. However even as terrorists the French are piling up failures, so it kept rolling with a living authoritarian in it.)
You could also get yourself a Citroën CX. I had two in a row so I can assure you it's a cool car, but more than that: Master Jacques Chirac, the King of the Thieves himslef, had one when he eventually reached the state of head of the state (some even go as far as saying he was properly elected, but I can't be that bold) and he toured Paris at night to celebrate, then went to collect the keys of the French Republic from the former (and defeated) crook who left in a black Citroën XM.
I'm sure you'll agree that's probably as sinister as you can get.