Generally lap times are rolling start. Couple warm up laps, then best times out of the high speed laps, then a cool down.
90 MPH average in a ‘sedan’ is quite good. I don’t know that course very well as I was an east coast racer, but on most any race courses there are curves that take you down well under 40 MPH.
I have ‘thousands’ of laps under my belt at Road Atlanta in F-production and would love to have hit a 90mph average. I was in a 4 cylinder ...
Fontana is a 2 mile banked oval. Not sure if they have an infield road course (like Michigan).