I know this is a done-to-death subject, but I searched the archives and
didn't turn up what I was looking for:

The facts, as I know them:

According to yesterday's "speedometer check" signs posted by the side of
Interstate 8, my odometer is a smidge optimistic: when I had traveled 4
miles, the odometer read 4.1 miles. Close enough for me. 2.5% error.

The speedometer reads pretty low. According to the "Your Speed Is"
automated trailers with giant speed displays parked on the streets AND
according to my GPS, the speedometer is WAY optimistic: when I'm going
65mph the speedometer thinks I'm going 75. This is a fixed percentage:
as I go slower, the mph error is smaller but the percentage error is the
same. About 8 - 9%.

So the odo is acceptably accurate, the speedo is not so accurate.
Anything a fellow can do other than just mentally correct the speedo
reading?

--

Mike "Rocket J Squirrel" Elliott
71 Type 2: the Wonderbus
84 Westfalia: Mellow Yellow ("The Electrical Banana")
Carlsbad, CA
KG6RCR