I am currently playing gran turismo 6 and while the cars look great (this is gran turismo after all) the enviroments look very poor even by 7th gen standards. Not only do the textures  look low res but they are still using cardboard cutout tree's and bushes, something i haven't seen in years. Ps3 may be really old but it can still produce gorgeous looking enviroments  so why the discrepency? why do some other ps3 games look like a generation ahead of gt6. I am not saying this for effect but apart from the upgrade in resolution enviromentally there really isn't that much difference between GT6 on ps3 and GT4 on ps2. Like i said i am talking about the enviroments, there is nothing wrong with how the cars look.

Update: This is what i'm talking about. Notice the cardboad cutout wall of trees.

I don't remember them being that bad for PS3 standards. Below is an environment from Forza 5, on a new gen system, and has some of the problems you mentioned

It didn't impress me when I saw some gamepaly for it. The game should have never come out on the PS3.

That still looks infinitely better than the foliage wall you see in gt6.

I don't think Polyphony Digital ever understood the PS3.

Yeah, I've seen some Sony fans boast about how great GT5/6 looks but they are kinda rough looking in some spots.
GT games on PS3 also suffer from frame rate drops, screen tear, and lots of jaggies. While Forza on 360 was more polished and locked at 60 fps.

Part of the problem is the GT games waste a lot of resources to push a higher resolution.

Everything in GT6 is an improvement from GT5, but you're right there were a lot of things that I think could have been implemented to improve the game further. Environmental details are one of them. Still waiting on collision physics, a better damage system, full premium cars, and better sound quality.

GT on ps3 has inconsistent quality in cars and tracks. Some are old tracks with minor upgrades. That track with the tree wall is 24h Le Mans, an oldie. There are much better looking tracks and environments. GT6 looked great for the time, didn't feel dated to me. Project cars however does already feels dated on ps4.

GT6 on PS3 looks sometimes better and more realistic than Forza 5 on Xbone... so I don't know what you talking about.

Your picture is from some GT4 imported track... show a pic from the new tracks for GT5/GT6.

GT6 runs on 1080i on 60fps...on PS3. It looks as good as it possibly can.