On the way to Dover they have a DVSA inspection area, they pull anything they like off for a going through and take their time, as the intercept cars like to keep the centre where they have all the space and kit, busy... Mainly big rigs, but if you are slammed to the ground, or they can say you look overloaded etc, they might just as I believe they even have a weigh bridge.....
In any case, it was an observation..
Another thing that is in the pipeline/being talked about for London etc, is the sniffers that can measure pollution as you drive past, and for the offender take a pic of reg number and issue fine.. This is future stuff, but worth thinking through.