I run it with all settings on High/Ultra but with Motion Blur set to off... It does look like in the unedited screenshots posted everywhere.
I think there are two things at work that make it seem like in-game there's something missing:
-Composition: Screenshoots are taken with very dramatic camera angles, positioning and settings such as FOV and focal field... Right now built-in track side cameras are pretty much copypaste from Shift 2. They are not very zoomy and most of the time their focal lenght and FOV is unrealistic... As soon as we're able to put them right were we want then and have them point at what we want with artistics settings, there isn't going to be any noticeable difference.
-Downsampling: Even the unedited shots and most of the in-game video captures are sometimes downsampled somehow, for example by the forum the make an image fit, or by file hosts themselves such as tinypic. This downsampling takes away some of the aliasing present in-game. Edited screenshots take this one step further adding a tad of sharpening.
There is now work being carried over in the FXAA are which will bring injection obsolete, BTW.