I have the Logitech Racing FF wheel (see pic).
In my experience, this wheel is superb for the majority of Mac games, and perfect for Windows games....
But...
I have an issue with Colin McRae Rally 2005 (both on a Mac Pro '08 and Quad G5):
The wheel works, but the preciseness is poor. I have to to minimize the deadzone, and fiddle with the responsiveness to make it "alright".
This same wheel in the same game in Windows XP works perfectly, and this same wheel playing any other game (Need For Speed Carbon on this Mac, or Nascar 2003, or F1 CS 2000 on a G5) is perfect too...!
I have also tried another wheel (an older Logitech Wingman Force) on a Power Mac G5 Quad running Leopard, playing Colin McRae 2005 and it has the same issues...
So, I am not sure if Colin McRae simply needs an update to solve the issue, or that simply the Logitech wheels are badly supported on the Mac version of this game.
Everything else works perfectly.