I never had any luck with mechanical car clocks. In the 70s I installed a blue florescent digital clock, trouble free and far more accurate. It dims when the lights are on; looked more at home in that square window than a round clock. Had a little trouble getting a complimentary picture of that self illuminated display here. Looked better in practice than this picture. An LED clock with bigger digits would fit the space. The clock set shaft was replaced with a button to illuminate it when the ign was off, but now its on my shop wall and lights with the other lights.
The other thing of note, is 219,699 miles on the odometer, first one I ever modified. Bruce Roe