In Palanga, Lithuania there's a 1000km (or actually 1003km because tv channel 3 spnsors race) touring car (and sports car) race on a motorway track.
Track:
http://www.promosportas.lt/uploaded/...03km_trasa.jpg
More info (regulations, results, photots etc):
http://www.promosportas.lt/promo/ind...=1000km2en.php