The trees in Autumn Ring don't impress me, but then again it's still a ps2 ported track with a slight makeover. But have you not seen the new tracks? There are 3D trees. Goodwood Hill Climb still has the best looking trees and most realistic looking out of any current gen game. Bathurst has nice trees, Spa has nice trees, etc. And NFS is 30fps with framerate drops, and doesn't even look realistic. I'm also not sure which Forza game you're playing but
those trees not only look like they're flatly lit with lighting that's completely different from the actual track, but they also sometimes have
muddy textures and not realistic at all. It definitely doesn't give off the illusion of realism like when you're actually driving on GT5's 24h nurburgring.
Spa's 2d trees still look more realistic and they're definitely not "low-res" compared to the games you mentioned. I imagine it'll only get better with the PS4