I've managed to crack this one with the Aston Martin DB10 Gr3 race car with 95% of power. It's great - the car has long legs so I can comfortably punch out two or three laps. Usually rains around lap 2, or halfway through lap 3 so it's on to Intermediates - not Wets.
Have tried with other cars - no success. The AM is the winner for me on this track. 550,000 credits for a win, but let's try to play nice and get the Clean Race Bonus.
Working on the 800 series - need to pick the right car and bed it in for this. Still struggling a little getting the right vehicle, but it won't be long before I crack it.