Came across this a while ago via GTP which adds some flesh to the 'changing seasons' seen in the recent leaked intro:
https://www.engadget.com/2016/06/07/online-gaming-was-his-gateway-to-professional-racing/
"What can be expected from the simulated sequel?
Stephen Viljoen: There will be some significant changes. We'll be taking you to new surfaces through rally and ice racing and the various aspects that go into simulating the systems and how you get to the championship. We'll have a lot of new cars, even brands that we couldn't have before. Now that we're on the map, people recognize us. They're more willing to come to the table and agree on prices that we can actually afford to pay for some of these brands.
We'll have multiplayer enhancements and more support for VR. We'll be polishing features for more authentic experiences. For instance, with the first Project CARS we had the ability to do a 24-hour light-cycle simulation; now we will also be doing season simulations. You'll see snow in the winter or different leaf colors for autumn and it will dynamically change so you can set it to go through the seasons. It has such an impact on racing. For freezing temperatures on the racetrack, you want visual cues to know the effects it has on the car. Same with rainfall: It happens in various stages, so we'll now have it sunny in one part but there might be a rain cloud a few corners away. It will have realistic puddles and how they affect the handling of the car. And it won't be pre-generated art; it will be simulated to the scenes. The slope of the track will determine where the puddles fall. This is all in addition to it sounding and looking better."
https://www.engadget.com/2016/06/07/online-gaming-was-his-gateway-to-professional-racing/