Tony Gardner posted some information about the switch to DX11 in the March Build
“Our major graphics engine upgrade from DX9 to DX11 is going very well although testing and work continues on various odds and ends. The massive list of work we had to do is pretty small at this point. Our current plan for the March build is the sim will default to the current graphics engine, DX9. However we are happy to say you should have the choice to load DX11 in the March build and try it out in your races or testing. You can go back and forth between the two if you want or if any issues with one or the other. Although we have been testing DX11 in Alpha for months we will still consider this role out to members in March to be part of that “alpha” testing process to iron out any issues. Hopefully there are few or none but you will have DX9 to fall back on.
Then our guess is in the June build it will be reversed. DX11 will be the default and DX9 will be the alternative option.
Then late in the year or certainly at some point we will stop supporting DX9 as it is very inefficient to keep developing for both. Additionally, DX9 at that point would be holding us back graphically and performance wise.
We appreciate your patience during this process as we migrated iRacing from DX9 to DX11.
“The march testing release of DX11 most likely will not include any Oculus Rift support – although we have been working on it! It doesn’t seem likely it will work fully enough by then. It shouldn’t be too long though until it’s ready.
The DX9 version will likely remain linked against the same Oculus SDK as it is now (I think that’s 0.4.2?). We really can’t bring DX9 forward because the newer Oculus SDK’s have dropped DX9 support, so DX11 support can’t come soon enough.”-Shawn Nash