Last winter, I purchased a http://www.scangauge.com/ as an alternative to repairing my broken gas gauge. After adjusting the speedometer function with a GPS to compensate for my 285 75R16 tires, the 'fuel used' function was always in agreement with the gas pump read-out within 1/2 gallon. (at fill-up, I run the pump on full until it shuts off, and secure after the pump shuts off on low.)
Last weekend pulled a 22' travel trailer on a 700 mile trip across southern Idaho. The gasoline varied from 85 to 87 octane, all was 10% ethanol. The trip was nearly entirely on freeways at speeds about 55 to 60 MPH. Again the gauge never differed from the pump read out by more than 1/2 gallon. The truck turned 140K miles on the return and got 9.9 MPG on the entire trip.
Considering the accuracy of the fuel feature and all the other functions it provides, ScanGauge is an amazing device.

 

I have wanted one for a while as my gas gauge is funny too. I've been looking for near a year now... but the extra funds arn't there to get one since the gauge does still semi work. Thanks for the review though. Maybe this summer I will pull the trigger.

 

Interesting. See they offer 12 different gauges depending on vehicle, but wonder exactly what they are for the Rams?