The good folks at Nadeo have announced a release date for Trackmania Turbo! 24th March 2016 (or 22nd March for USA)
Meanwhile, check out the newly released video showing off the 4 environments featured in the game:

Trackmania Turbo – 4 environments, 4 driving styles

If the above video isn't available for you... try this link:
Same video for those in the USA

Not long now!