I would imagine that car customisation began shortly after the invention of motoring itself, certainly it was popular between the wars with the advent of the hot rod, cars modified to get them to look better and go faster. The TV programme
Pimp My Ride transferred this to the small screen in 2008 and spawned versions around the world, including the UK.
This little selection came from a series that appeared in the magazine
Popular Motoring during the early 1970s, a bundle of which I have recently acquired.
A cheaper option is just to spray on some cool colours, even your old Austin Devon apparently......
Ford Populars are popular...........