Just figured it out.
Trackmania can't see the difference between the Nvidia onboard GFX card and the Dislaylink drivers for a USB gfx adapter. Had to uninstall them.
Then it detected the right drivers.

This was an annoying bug!

TM2 complains about outdated Nvidia drivers. Tried to upgrade drivers and now I'm running on latest Nvidia drivers for mye laptop, but it still complains and won't start up. Running 285.27 on Windows 7. Gfx card on the laptop i 8600m GT. Any suggestions? Tried to uninstall, reinstall several times.