I was getting frustrated with the options available for testing cars at high speed - so I made my own test track. https://steamcommunity.com/sharedfiles/filedetails/?id=2940115983 It's still bare bones as I am using it as a test bed in itself for generating procedural stuff for a range of circuits - but it does the job that I intended for car testing with a high speed 7.5 mile oval, skid pad and winding road course (the road course is a bit of a placeholder until I get better data for the road surface). Since it is still of practical use even before all the bells and whistles are included I've put it up on the workshop.