Tnx Sawen for your work and progress report on gfx/physics. Might be worth thinking about some number for the gfx update rate which is an integer multiple of the refresh rate, like for example 120Hz. Would be beter for 60, 90, 120 and 240Hz screens. Then subupdates at 8×, giving 960Hz.
About optimizing environment checks, one approach that comes to my mind is to create at least 3 spacial zones around each important car propertiy. Each zone would have an increasing update rate checks, as the radius reduces. This way, one could save some CPU time, by avoiding unecessary checks that would not lead to collision.