Well, I must disappoint you. I'm not a professional historian, just a mathematician working in the IT business.
In this case, the puzzles just perfectly fitted my special interests: German and French cars, and especially microcars. And I must admit, as I saw these puzzles moving towards the end of the Rookie chain, I prepared the answers. So you can see, no witchcraft involved. Well, being interested in automotive history for about 40 years, I seem to memorize just the necessary keywords in order to google some helpful information, or I know in which books to look. But don't worry, I still have the feeling that most puzzles in here leave me clueless.