If there were to be one major change to forza horizon 3 I would hope they had local drop in multiplayer, like having your mate grab the controller next to you and play. I also hope to have the power to put down and and up convertible tops. Now those two major improvements would make forza the ultimate game and separate them from other car simulators.
By local multiplayer I take it you mean both of you on the same machine.
That would be a nice feature but it won’t happen. The open world is too vast to hold two versions of it on the same system, seeing as each player could be at opposite ends of the map at the same time. The systems couldn’t (currently) handle it, either PC or Xbox. The closest would be some kind of system link/LAN setup and I don’t know if that’s possible with this game.
There’s a whole other thread on convertibles and that would be achievable but we’ll have to see if it’s added at any point.