Cops and Robbers has been a thing in LFS for a very very long time. Back when there was no wrong way detection, playing it demo servers used to be a blast. It's really the whole predecessor to cruise servers.
Best case for compatibility would be using Bootcamp to install Windows.
Else the support is hairy as recent OS X doesn't support 32 bit applications, so running LFS inside of normal WINE won't work.
There's a proprietary version of WINE called Crossover which has done the work to run 32 bit Windows applications inside modern version of OS X, but the application does cost money.
Another option could be to use the free version of VMWare Fusion to run a Windows VM. Windows ISOs are freely available and work for like 30 days without activation.
I don't have a DD2, but it might be because of button/axis restrictions. Because some of the addon wheels support a lot of buttons, where some versions (all?) of DirectX only support 32 (64?), so it exposes 2 devices to split the buttons so it can have more than the maximum
Oval Racing isn't much fun with only 2 ovals, both of which are very atypical compared to most ovals. One of which has been so unsuccessful IRL that it's not even a race track anymore.
I feel like iRacing's damage repair is (for the most part) a bit more reasonable. Hard hits do take likle 30 minutes to fix sometimes. Only part I find "off" is that a 30+ minute repair doesn't leave the car driving well in many cases. You'd think if they rebuilt the suspension or something that they'd have aligned it even a bit correctly.
So your PC can't maintain a steady 60 FPS if it drops down to 30 FPS via Vsync in some situations. "Steady except sometimes" means that it's, by definition, not steady.
The texture mods that you are using could be placing additional load or paging on the system, leading to missed frames and frame drops.
A background process could be stealing enough CPU time at the wrong moment to cause frame time to take too long, dropping the frame rate.
Again, it could be possible that for the races you're running, with the settings you're using, the mods that you're using, that your PC is just too weak and can't maintain 60 FPS.
Disabling vsync would help (albeit adding frame tearing) by ensuring that a slow frame doesn't immediately halve the frame rate.
If it's dropping to 30 FPS then you're not able to maintain 60 FPS in those situations. If you were, it wouldn't drop to 30. Additionally, dropping to a divisor of 2, 4 or 8 of refresh rate is a symptom of double buffered vSync.
The settings in nVidia control panel for vSync applies to OpenGL games, not DirectX. DirectX also has some problems with triple buffering in older versions of DirectX, in some cases it's just unsupported and in other cases it creates further input lag or dropped frames. It's also up to the game to support.