the thumb & index finger formed into an 'o' + the other fingers straight up and the hand waved back and forth means like 'spot on' or 'ok' in uk.

We used to have it in that sense as well in Germany, but in the younger generation of drivers the 'o' formed by thumb and index finger (no hand movement necessary, but that's hard to spot) means 'asshole'.

And of course a big 'O' formed by both arms with the fingers meeting above your head means 'giant asshole'.

Wolfgang