Hi Col, welcome aboard. Theres a few of us who are keen motorsports photogs here, with 4 or 5 CAMS accred members.
I know EC is a pain in the ass to get around, but you should try to shoot with the sun behind you, rather than into it. Shoot fromthe western side of the track in the afternoons and vice versa. Avoid shooting at midday, unless it's pit chicks
By shooting into the sun, the camera exposes for the shaded area of th car, which tends to blow out highlights. If you are shooting with the sun behind you, even though the car is brighter, the camera exposes properly. Does this make sense? My brain is still full from the XXXX angels....
I didn't shoot a single frame of super karts, but from what I heard they are a bugger, because of their size and speed.
Nice images all round. Look forward to more.