Had a look over the track list. None of the city tracks have day/night or weather, such a shame. Would also have been nice if Suzuka and Laguna Seca has day/night but alas. Thanks be to Kaz that Spa has day/night. Good to see Tsukuba got rain back though.
Dynamic time change on a city track is probably very taxing. So much more lighting to deal with.
Anyway, here's some info from the site:
User Interface
Starting from the My Home screen where the game begins, the user interface has been thoroughly re-designed and refined, allowing essential all features to be quickly accessible and simple to use. The time taken to switch between screens has also been significantly reduced compared to Gran Turismo 5.
Career Mode
This is the main scenario mode of this game, where you begin from the entry level and gradually acquire higher level licenses. With a new system that allows you to progress by gathering a per-requisite number of stars, progress in the game can be matched to your skill. Many types of events have been made available: later in the game there are particular events where the weather conditions change continuously. There are also events that recreate the feeling of endurance races in a much shorter period of time.
Winning events will award in-game credits that can be used to purchase cars and parts.
Coffee Break
These are mini-games that appear between events in the Career Mode. There are many challenges that can be tried over and over again, such as a cone knockdown event inside a stadium, and eco-challenges where you compete for how far you can drive on just 1 litre of petrol.
Special Events
These Events are unlocked as you progress through the game. For example, you will receive invitations to the prestigious Goodwood Festival of Speed, and you can look forward to even more events to be added in future updates.
Car Dealerships
All available cars are displayed under their respective manufacturers. There are no longer distinctions made between Premium and Standard cars as in the previous version of GT, but Standard equivalent cars will only have simplified cockpit views.
Featured
This is a dealership that specializes in cars recommended for clearing the Career Mode, cars by racing category, and cars that can participate in the online events. If youre looking for a particular car for a particular purpose, you can find it easily here.
Garage
Organizing and managing the cars you own in your Garage is now much more straightforward. You can also try out your cars on Free runs and change racing gear directly from this location. You can also store cars you dont normally use in a Stockyard, and transfer to your Garage when required.
Tuning Parts
Here you can purchase a variety of parts including tyres, suspension and brake kits, transmission, clutch and flywheels, exhausts, superchargers,
nitrous and others using in-game credits and you can also tune engines and car bodies.
Custom Parts
Purchase aerodynamic parts and over 82 types (with 188 variations) of wheels using in-game credits. More custom parts will also be added in future updates.
Pit Service
Car wash, oil change, body reinforcement, body maintenance, and engine maintenance are all performed here.
Racing Gear
Racing gear for your in-game driver avatar can be purchased here using in-game credits. At launch there are 34 types of helmets (with 952 colour variations) and 28 types of racing suits (with 852 colour variations) as well as special racing gear sets modeled on racing gear of famous real life drivers.
Paint
In addition to car body paint supplied in the colour of the cars you have acquired, in the future there will also be special paint items that will be distributed in online events. In addition, it is also possible to paint wheels purchased in custom parts.
Stuff that will be added in future updates:
B Spec
The B spec mode is a mode where you give precision instructions to your driver as a race director. This popular feature from previous versions of GT will be added in a future update. Look forward to the new, more powerful B Spec mode.
Course Maker
This feature, available at a later stage through an update, will allow you to create your own custom tracks that can be driven in the game. Additionally, in another update we will add the possibility to generate a track by capturing the GPS coordinate data of a mobile app while you are driving that course. This GPS-generated tracks will be available in the game as playable content.
Data Logger
This feature allows you to analyse your saved replay data to show Speed, Engine RPM, Throttle Input, Gear Position, Steering Angle, etc. in a graphical format. This feature will be added in a future update.
GPS Visualizer
In a future update, we will add the GPS Visualiser. This is a feature that allows you to import Controller Area Network (CAN), used to regulate automobile systems, and GPS coordinate data from a real life car into Gran Turismo 6, and visualise the data as a replay in the game. The feature is planned to be compatible with the Toyota Motor Corporations CAN-Gateway ECU.