I follow 'Hoovies Garage' on YouTube, and today he bought an '04 Ram 2500 4X4 Diesel with (supposedly) just shy of 1 MILLION miles on the engine. Says the Carfax backs up the claim.

BUT, in the video, he points out the factory computer that shows MPG is VERY optimistic. It showed 30 MPG average at his first fill up when in actuality it was getting 18 MPG.

My question is, could the odometer be reading 'optimistic' like the MPG is? Just curious.