Before each race weekend IRL I usually find a track similar to the one I'm racing at in NR2003 (almost every oval in North America has been made at this point), and do a full 100 lap "mock race" against a similar sized field of cars and my own custom AI path. People really do not understand just how close NASCAR 03 is to the real thing in terms of tire behavior and vehicle inertia. Few seasons back I had never driven on slicks before (our series uses grooved slicks to prevent guys from blowing $$$ on massive motors) and warmed up on NR03 using some track in Wisconsin as a placeholder. Went out and set the track record in qualifying. Pedal and wheel inputs were basically 1:1. Our baseline setup also works in the game.
IndyCar Racing 2 I recently got up and running on DOSBox. With a wheel set to the correct rotation it's quite fun both on road courses and ovals and it's the only IndyCar game I've played where races generally play out like a proper indycar race - draft battles on the ovals, lots of space between cars, AI with noticeably different skill levels between drivers, that sort of thing. I think what makes the experience is that with such simplistic AI, there's less chances for bizarre stuff to happen like you see in the isi/Madness engine games where cars divebomb the daylights out of you, drive on the grass, etc.
NHRA 2 and NHRA 2007 also get regular playtime, mostly because nobody's made any sort of drag racing game at all over the past decade. The team who made both games were massive NHRA nerds and most sim racers would not be prepared for how meticulous the engine adjustments are. The game is uncompromisingly difficult on max difficulty and both games have a proper career mode. Usually once a year my buddy and I will order pizza and just blitz through a few seasons, trading off every event.
Lastly, it doesn't count as a sim, but GeneRally. One of the best racing games ever made and it's a shame it never received an online component. The library of content for this game is staggering and it plays like a sequel to Danny Sullivan's IndyHeat.