Trials HD (XBox 360) uses Bullet

trials_hd“We are also using a modified version of an open source physics engine called Bullet Physics Library to calculate our physics simulation and collision inside the game. We have in-house optimized it for the Xbox 360 CPU and vector units. Our game engine is designed to be fully multithreaded, and we are simulating physics at the same time we are processing game logic, graphics, sound and particles in other Xbox 360 hardware threads. With extensive optimization, we have achieved a very good balance, with all six CPU hardware threads constantly working under heavy load.”