Ha, so Slightly Mad's rant over the original preview was all for nothing. I'm not seeing any improvement.
That said, these situations are setup to test the game at its limits. The average race, on PS4 at least, seems to hold a pretty darn stable 60fps. It's just when you massively bump up the number of cars and add weather it can get pretty awful.
The Xbox One version, though? Just awful all around.
Still, it looks like they did a pretty good job overall on PS4. They could have eliminated races where the frame-rate can dip by removing features but they chose to allow players to push it up to the max at the expense of fluidity.
I wonder how DriveClub would hold up with an unlocked frame-rate? Something tells me we would see a fairly smooth 60fps in many situations but similar drops to Project CARS with weather and other effects. After all, that game holds 30fps 100% of the time so the general performance level has to be well above that.