wrote:

'occasionally drift over the speed limit' = 'habitually and wilfully
flout the speed limit.

As in "I just drifted over the 30 limit".

Well, to get nicked you have to be doing 35 in most police force areas
(10% + 2mph). Most car speedometers are around 10% "fast", so that
means you just drifted up to 37 or 38mph. That'll be £60 please, thank
you for playing.