Yes, it's Mt. Haruna with some creative liberties taken.
Some pics from Haruna. You can find more
here.
I think the problem would be rights to the Mt. Akina in the anime or manga. There is an Initial D licensed game, so they can't just ask Shuichi Shigeno for it. It would depend on what the contract is with SEGA. Getting Haruna though would be easy. The Tokyo Extreme Drift series had it. That's probably why PD refer to the AE86 on GT3 and 4 as "Shuichi Shigeno Versions" instead of giving a direct reference to the anime. No Tofu shop decals on the side either.
I'm all for a touge type event/track. 👍👍👍