I may be wrong, but that old chestnut 'what would you do if you were locked in the car and only had a hammer with you' springs to mind.

I think the answer is that you pull up the lock knob thingie on the door sill, to open it, and thus get out.

Maybe doesn't work on all cars ...

"Watch out for the pedestrian ..... It's on the road; it knows the risks its taking!"