I use my Garman GPS for the speedometer as it is spot on, the in Dash spedo jumps around, be going 62 and it jumps to 70, 85 then back down etc... It`s most likely the cable.
The odometer works ok, but compared to the GPS is off.
Also use the GPS when I fill up to keep track of each tank MPG.
My Fuel gauge does not work, so with the 38 gallon tank, I fill around every 500 miles, figured 600 is max.
We just came home from a tip to Colorado Springs. Filled up in
William`s, Az, it`s west of Flagstaff on Hwy 40. Drove through
Las Vegas then north on Hwy 95 through Nevada, and finally home near Carson City.
Couple days later headed to town for something and decided I
better fuel up. 10 miles to the station from the house.
Drove 690 miles,
put in 38.045 gallons
got 18.14 MPG.
Cut that one pretty close. I always fill to the tippy top of the fill tube. So a good gallon or more? Let`s say I ain`t cuttin it that
close again.