If your computer is not powerful enough to play the upcoming Forza Motorsport 6 Apex on maximum settings (more on those specs here), you can use the included "dynamic resolution" function that Turn 10 has added to the PC version of the game.
Forza 6 Apex will, on its own, change graphical settings in real-time to maintain frame-rate and, from what we've seen in the open beta, it works perfectly.
• Performance Target
Set the target frequency for render and game thread updates. Some players made experience smoother rendering by lowering to 30FPS when higher frame rates can't be maintained.
• Dynamic Render Quality
Set the target visual quality level for the experience. This option is set by default based upon your detected hardware, and increasing it can have a significant negative impact on performance.
• Dynamic Optimization
Adjusts visual settings dynamically, to maximize performance for any given gameplay scenario.