I'm not sure they are 'cleaning up' in Europe now- last years FIA Championship win for Larbre was achieved with only a single race win- the Spa 24hours, which carries extra championship points, and there were only a couple of other Viper wins all year (one for each car of the Carsport team)
http://wsrp.wz.cz/fiagt2002.html#2
The Lister and Ferrari were generally faster, and won more races, but didn't have the consistency- With more Ferraris and a stronger Lister effort, plus 3 Saleens out there, I'd be very surprised to see a Viper win regularly this year....