List of changes for v18/Targa (v17 was never released publicly)
Best laps are now saved persistently to disk into the "rFactor2\Userdata\player\Settings\DeltaBest" folder. The format is "<TrackName>_<CarClass>.lap". For now this feature can not be disabled, but read the ResetKey entry below.
Plugin should now work fine with the Targa Florio track. Previously there was a hard limit of 50km long tracks.
Delta time is now displayed beyond the session end time. This typically impacted qualify sessions. When the session timer reached 0:00, the delta time disappeared. Now it continues to work until the session is closed.
It is now possible to reset the best lap of the session through CTRL + Z. I realise this shortcut may not suit everyone, so you can customize it through the DeltaBest.ini file. In the "[Keyboard]" section, the "ResetKey" entry will allow you to redefine the ResetKey.