Clearly Turn 10 were hard pressed to finish Forza Motorsport 5 in time for the Xbox One launch. They did a great job, but have received some criticism regarding the number of cars and tracks, and also about the lack of night-time racing and weather physics.
Creative director Dan Greenawalt talked to IGN about these issues and said it takes nine months to finish a track for Forza Motorsport 5 and adding night and weather to the mix to require much more time.
Turn 10 are obviously hard at work updating and improving Forza Motorsport 5, but don't expect night-time and weather to be added as it would simply be too much work.
"If we wanted to make one of those tracks work with the added particles or projected shadows, and of course adding the physics to do something like night and wet, it means re-engaging those tracks. I'm not trying to give an excuse, I'm trying to give context as to why this is an order of magnitude higher than something like Drag and Tag, and other things we're looking at from the community."