A simple WPF app to give you telemetry from Assetto Corsa. Just press start when you want to start and it will create graphs like this:
The performance impact is minimal, I have a pretty poor machine and I don't lose more than 10 FPS. The graphs are made with this library: https://github.com/swharden/ScottPlot
In theory this should work in Assetto Corsa Competizione, however I don't own the game so I haven't tried.
This app can show the slip of each tyre individually:
Note, I'm not actually this bad, I needed to spin on purpose to demonstrate the idea (insert Sebastian Vettel joke here).
Check the releases page for downloads. Run the InstallScript.exe file and you should be good to go.