I think, if we do get a snowy environment (which I think is likely), I'd actually like to see it mechanically be a modern take on Coast and its realistic driving. I always found it odd how the Snow environment was exceptionally grippy and zippy but Coast had a car that slid all over the place and was sluggish to get going. But I think a lot of ideas can be merged here, actually. As odd as it might seem, putting Coast's GP-style roads in a tundra environment isn't unheard of - I'm particularly inspired by Arctic Circle Raceway, up in Norway.
I think I have a vision for a compelling setting: Siberia, very specifically a particularly Soviet slice of Mongolia. Wide rolling hills that aren't permanently snowbound, but frosty and cold-looking, cliffs that hide frigid deserts and sand dunes like the Gobi, yurts, big-blocky Russian apartment buildings (they even look like Trackmania blocks in real life - forests of the same building, but you can claim they're realistic now!), massive statues of Genghis Khan, maybe an old temple here or there, you can even throw in that idea for having some old rusted-out industrial stuff. Tunnels can be bunker entries into sprawling abandoned missile silos, maybe related to the 'platform' of the environment, which overall would have a very military feel.
Car could be a trophy truck, or maybe it could be something more luxurious - a big boat of an executive sedan, maybe? Both work for Coast-style gameplay, slow to start off and reliant on keeping your grip, where if you slide you've probably messed up. While I like the vision of a big land-yacht, I admit the truck with honeycomb wheels is more solid, and gives me another idea - maybe in this environment, you're slippery and slidey on asphalt, but you have an incredible amount of grip, control, and speed off-road. May not work so smoothly though - too much incentive to just hop off the road to go faster. If you're doing that, a specific tile that enables this off-road grip might prove necessary.