I'm always interested in finding fairly simple but good paper cars. Here are a few new ones to try out.
This page has five Nascars and they come out just the size of matchbox or Hotwheels cars! Super easy to make. Then you can make a whole set with roads to go along with them. Found this image on a google search, but the main page is listed on the printout and you can click here to see the source which is in French. :\
http://maquettes.hautetfort.com/
Here is a paper craft blog in Russian with lots of great vehicles. Here's a sample of them you can download, and the link to see all of them
😀😀😀😀