Turns out the police Riot Van has a bulletproof windshield. You can't shoot people out from the front, but you can shoot people out through the door windows if you get around to the side.
Basically I got killed by it once then got a hold of it myself and went on a massive ungodly rampage. Actually the riot van is arguably better than Rhino tank, because using it doesn't automatically give you 5000 bad-sport points.
So are there any other vehicles with bulletproof windscreens? (Well I think the Annihilator and the Cargobob also have bulletproof windows, but I was more looking for cars). I think I'd heard someone suggest that an FBI Van had them too... but the normal FBI SUVs definitely don't and maybe they meant the Riot Van.