This will probably be a controversial statement, but I find Forza 6 (mainly the photomode pics, won't get into the gameplay/framerate discussion) quite uneven looking due to two factors; the lack of tesselation and the bad lighting/shader setup. The second factor is by far more impactful.
For example, the car in this pic (credit: G Rom) looks like some kind of playdo model since the shaders and lighting are so dull:
Same here (credit: shinnn), the car looks more like a low-grade render than something even remotely real, even though the actual geometry of the car is nice:
And regarding the tesselation, this is very nitpicky I admit but there are quite a few sharp edges that break the illusion, especially since quite a few other edges are curved nicely. Take the contour/whatever-it's-called at the base of the windshield here (credit: G Rom), the polygon edges are rough especially compared to everything else:
Thus, if we go by pure
photomode looks, I think Forza is still doing somewhat of a poor job compared to some of the other games, especially since the Autovista mode has been through a couple of iterations already.