One drives at a sedate 120 kmph along the Danish motorway to the border with Germany. Not so long ago there were guards controlling this boundary.
One stopped or came to a rolling halt. If you were sufficiently ethnically correct you’d be waved through. Or, if they didn’t like the cut of your jib, a quick look at the passport might have been required.
Either way, one usually had to go from standstill or walking pace back up top speed (unrestricted on the German side). At this point I commonly experienced a shock as a car doing light speed would zoom past, seemingly having accelerated from near-zero (just like me) to 220 in the time it took me to get to