I have several pet hates when it comes to model road vehicles. The first is over-shiny paintwork. The other is bright colours.
In the steam era, most cars, indeed most of the world, were painted in dull shades of murk. Today's gaudy shades were but a dream.
I'm reminded of this when reading a useful article on the red paint offered by Volkswagen over the years. Despite some of the best engineers in the world, the first red didn't appear until 1956 and even that was a pretty dull. Over time things got stronger and brighter but you'll need to wait until 1968 for a really glowing shade.
While this only covers VWs, the rest of the automotive world was much the same so if in doubt, as the Rolling Stones would say, paint it black!