If 2 junkies jumped in my car with a knife I would put the boot down up to 100mph and then stand on the brakes (guarenteed their not wearing any seatbelt) ala Vinnie Jones
Seriously though - It's a very good habit to lock the doors whenever your in the car - I tell the other half never to stop for anyone even if they are lying in the middle of the road - keep on going and ring the guards

And if you ever think your being followed drive straight to a cop shop without stopping....
I was once coming home from Cork in the B4 and a lad jumped out of a jeep and started to bang on my window when I was stopped at lights in Fermoy - I put the foot down and they came after me flashing their headlights - I could see there was 4 of them i the jeep and they looked a bit dodgy so I kept the foot to the floor and lost them for a bit but I could see them trying to catch up with me so I slowed down and got their reg and rang the guards - when I gave them the reg they asked my name and what I was driving - they then told me I better stop as it was a special branch vehicle :lol: I pulled in a mile or so down the road and got out of the car - they pulled up behind me and jumped out flashing their badge - I just said 'I know who you are now as I rang the guards but I wasn't stopping for you before as you didn't identify yourself' - he just said 'Your dead right not to, now mind yourself and take it easy'

They then took off and gave me a wave

Never did find out why they wanted to stop me in the first place