I know that George Carlin was so much more than the voice of Fillmore in Cars. I'm quite familiar with his work other than the Narrator for Thomas and Friends. I just found it interesting and rather sweet that he would do this work (along with Shining Time Station) which seems so opposed to his filthy-mouthed, pessimistic, crass comedy routines.
I appreciate his work as a comedian who said what you were thinking and thought of things in ways I hadn't. I didn't always agree with his views but I certainly got to thinking about and defining my own views on subjects he discussed.
I'm saddened to hear of his death.