The only people who think Project Cars looks stunning are people who haven't actually played it with the monitor right up close to their faces and people who love substandard track/scenery textures and jaggies galore.
It's the single most overhyped game ever in terms of graphics, they are nothing special at all, in motion its ugly... yup i said it, UGLY. It's messy, full of visual artefacts, object pop in etc.
Racing sims need to be as clean looking as possible and incredibly smooth in motion, project cars is neither of these things.
AC has similar issues with visual artefacts (flickery shadows etc) but its nowhere near as bad as pcars and it runs a lot smoother as well (whilst also having good physics, something pcars will never have)