In English, that's a ``speed bump''. (Well, American English, anyway. I don't know what they call them in Britain.) ``Sleeping Policeman'' is pretty funny, though. I'll have to start using that in everyday conversation.

I have a 1987 BMW 325e. It doesn't tilt down much. Five degrees at the most, I'd say. I've always assumed that it was to avoid glare off of the stereo's face plate, and it certainly does that well.