Thanks for replying Axel.
The "allow game to adjust settings" box is checked. The thing is that I couldn't uncheck it even if I wanted to. No changes I make on the settings page can be applied. The "combined" box is not checked but GPL behaves as if it is.
I've got a horrible feeling that this is terminal
This is specific to the DFGT but may apply to the G25. If the Logitech Profiler's not been updated in a while try that, as it may enable some more options that the standard drivers do not offer. Within "Global Device Settings", for split axis, make sure the tick box "Report Combined Pedals" is unticked, and "Allow Game To Adjust Settings" is ticked. Note that any changes made within "Specific Game Settings" may not take effect unless the path to the specific gpl.exe is set. From my personal perspective, I don't use specific game settings, I just set a default and use that. That being said, GPL is the only racing game I presently play, so if you do need specific game settings, make sure the path to it is correct, as GEM+ and iGOR will use the modified exe rather than the original one, e.g. for 67s it will use gplc67.exe.
Hope this helps!