After a deep dive into the world of PC racing games, I've found that the one with the most realistic physics is, hands down, Assetto Corsa. This game is praised by most racing enthusiasts for its accuracy in simulating real-world driving physics. The way the cars handle and respond to different terrains and weather conditions is incredibly lifelike. It's not just about the speed, but also about the feel of the car, the grip, the tire wear, and the realistic sound. So, if you're a fan of realism in your racing games, Assetto Corsa should be your go-to.