BTCC/WTCC would be great. I daresay people online would find them refreshing because here's a true circuit-based professional racing series where aggressive, contact-heavy driving is par for the course.
Instead of Indy cars, how about this: Champ Cars. Use the Lola/Cosworth Ford setup circa 2004-'07 and just pre-Panoz DP01. This way, you can get the Champ Car experience without having a bunch of functionally-identical models all just made by different people. They are at home both on ovals and on circuits, and drivers could get to experience a piece of racing history that doesn't exist anymore, but when it did, it was quite entertaining. A lot of people would probably use Bourdais' car, but again, by 2004 the Champ Car World Series was basically a spec series, therefore that does not make any of the other cars uncompetitive or something. Also, from a tuning standpoint the Cosworth V8 they used in Champ Car was designed to be turbocharged anyway.
Drift competitions are a must, and sometime in the future there must be competitive drifting with prizes on the line. Car choice is just about nothing but a matter of personal preference from what I've seen, but if we get organized drifting competitions in Gran Turismo, a few cars are a must, like Sam Hubinette's Mopar Viper and the spellbinding Hankook Porsche. PD managed to sneak in Porsches by way of Ruf, so it's possible...
