In the '60s in my native English Midlands the police ran "Q cars" (Q for quiet), Mini vans the same beige-brown colour every grocer or baker seemed to use for home delivery (yes that was a thing then) with patches of CureRust on the side (fake on the police car),3/4 race Cooper S mechanicals, two lights which flipped up into the rear door windows (one said STOP the other Police), a flashing blue dome light which popped up through the roof air vent and two tone horns behind the grille. Almost impossible to detect apart from the bulky passenger - grocers usually travelled alone! And then there was Ford's Supervan, GT40 below and Transit van above. Rolled out to race meetings, one lap at the speeds you'd expect from a Transit van, 2nd lap at the speeds you'd expect from a GT40 to the amazement of all. Then driven home! Not impossible to pick but hard to pick at spectator distance at the track! https://www.motortrend.com/vehicle-genres/ford-transit-supervan-history/