Perhaps of interest:
I have compiled a list of automobile race meetings in six European countries, specifically the Benelux nations (Belgium, the Netherlands and Luxembourg), Switzerland, Austria and Germany.
The list is a work-in-progress, but lists around 3400 dates already, sorted per circuit. The pdf-file, called Auto Races Index, is available for download from http://www.wegcircuits.nl/ari.html.
Comments, additions and corrections are always welcome of course.