For next forza I'd like some further refinements in various fields:
1) multiplayer
bring back ability to create
open lobbies.
bring back various snippets of info when racing, like distances to car back/front, delta, etc. make this user customizable in display/positioning.
throw a bone to the people that want more options, and offer for those who want practice laps for positioning and pitstop strategy (I dont care for this personally, but I respect the wishes of other players I know indeed play and enjoy)
2) replays
I feel like replays just dont do justice to the game. I'd like a small team inside t10 that their single specialty are ..replays.
from placement and camera movements up to good cinematography. special attention as to how the replay engine takes the data points from the race and draws the cars. I know its only at half the framerate of the game itself, but what choppiness I see I do not account it on framerate but rather on the way the replay engine plots. turn 10 has still much to cover in this field, should they want to.
3) precision
I think t10 switching to laser scanned tracks was the best news for me on f5. I want this trend to continue and be turned to eleven.
Also physics side (which I find real good, a step up from 4 and very enjoyable (sim steering with tx is a handfull)) and even tuning side, these aspects which are great right now can became even greater.
edit:
leaderboards!!
I want elaborate leaderboards, am not happy as they are now.
-Career races should have their own leaderboards. ok, you got the best lap (even if with a car not allowed in the career race), but lets see who got the fastest accumulated laps time -and clean too- in that race.
-Per Car per Class leaderboards. who's got the fastest tuned mk2 gti around nurburgring? and in which class too. (this is a great omission for me)
Older forzas did have separate career races leaderboards, and while they didnt have the per class per car leaderboards, at least they kept locally the best laptimes of your five fastest cars per class around each track.
night/weather: I really dont care for those. even if we had consoles that could push these effects on top without having to restructure to find the juice, I would still complain for the valuable (for other stuff) time missed on those.
and hopefully those that think that its alpha and omega of racing will find their happiness in horizon2 and driveclub and stop bugging me with that stuff. what they did in previous games offering the same track in different conditions to choose from was good enough for me.
personally I think that there is still a lot of road that we have to cover on dry tarmac on sunlight, before we set our goal to replicate wet conditions at night. or even worse, dynamic transitions of sunlight to moonlight
seems too superficial for my tastes
now, dont take my words wrong, forza is my favorite franchise and I really love forza 5
but enemy of good has always been better
cheers