Rockstar North posted a job listing for vehicle physics programmer. It's a full-time permanent position. Potential employee will help maintain existing vehicle systems and expand them to support new features throughout the lifetime of studio's projects.
The programmer should demonstrate experience in C/C++, knowledge of real-time rigid, multi body simulation and Newtonian mechanics and strong maths skills (linear algebra, trigonometry, matrix/quaternion math). Also Rockstar will ask for a demo video or code sample of personal projects.
Curiously, cars physics in GTA 5 and GTA Online hasn't changed much over the years. This means that Rockstar Games may be interested to push it on another level for GTA 6.