From what I'm reading, the Black M4 is gone, and it seems it was put in initially by mistake, as it's the prize car for the Asian BMW TT evnet.
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Undocumented update changes copy/pasted from GTP...
This is the main part of the update:
Additional Features in the Open Lobby
- [Time Trial], [Drift Trial], and [Free Run] have been added to the [Race Type] option within [Room Settings] of the Event Settings screen.
- It is now possible to also [Filter by Performance] even when [Car Selection Method] is set to [Filter by Make] or [Filter by Category].
- It is now possible to select Karts in one make races held on weather enabled tracks.
- It is now possible to check regulation settings in the confirmation popup dialog before entering a room.
- In the [Race Alone] mode for the Qualifier, cars other than yours (when only spectating, cars other than the one in focus) will appear as lines.
Multi-monitor Compatibility
[Multi-Monitor Settings] has been added to the [Start Button]>[Options]>[Display] options.
Car Search
A [Car Search] feature has been added to the [CARS] section in My Home. You can specify the desired parameters to search for a particular car in the Car Dealerships.
Sale of Racing Gear in Individual Colors
The sale of Racing Gear has been changed from full color sets to individual colors. Some of the pricing for racing gear have changed accordingly.
Kart Adjustments Options Expanded
- [Traction Control] is now available to adjust in the [Driving Options]. [Skid Recovery Force] is also now available.
- [Brake Balance] is now available to adjust in [Machine Settings]. Only the rear can be adjusted in Normal Karts, while both the front and rear can be adjusted in Shifter Karts.
Other Improvements/Adjustments
- An icon that shows the login bonus stage (1-5 days in succession) has been added to the top of the [My Home] screen and the prize receiving dialog.
- The increments of the [Front/Rear Torque Split] in [Car Settings] has been changed from 5 to 1.
Also, people are reporting major improvements in the appearance of some "standard" cars, and all open cockpits cars, are labeled as having "detailed interior".
Also, also, the pit stop tire bug is supposedly still present. Not sure I even care enough to check it anymore.