As a mainly offline/solo player I would love a feature to be able to pit 2+ of my own cars against each other. A drag race would be an awesome start, a circuit even better.
I usually only conservatively modify my cars, kind of mimicking how far I would take them in real life. I just noticed my BMW M6 is kinda close to my BMW M8 Competition in spec (although the M8 is AWD so would take it off the line). I’d love to see the two thrash it out, then add in other M cars to the mix too for some shootouts.