Anyone have a trip computer in their 2nd Generation or older Ram that gives real time mileage and works well?

I've looked at some online like the Roadi TG3 Turbo Gauge 4-in-1 Vehicle Trip Computer, Linear Logic ScanGaugeII 3-IN-ONE Automotive Computer Fuel Saver, Auterra A-500 DashDyno SPD In-Vehicle Automotive Computer - Scan Tool, Performance Meter, and Data Logger, and PLX DEVICES MPG METER AUTOMOTIVE COMPUTER.

Dealers say these devices plug into the diagnostic OBD-II connector found under the dash on 1996 and newer cars and light trucks. I'm skeptical. Does the computer know what the fuel flow is at that moment versus the vehicle speed?

Thanks,
Cody
1996 Dodge Ram 1500 4X4 SWB
5.9 with auto

 

The truck's computer knows the fuel rate and the vehicle speed, the scangauge takes that data and turns into information that you want.

 

Yeah, I'm looking for the same thing you are. I have narrowed it down to scanguageII and the Bullydog Watchdog. Think I'm gonna go with the Bullydog cuz of the larger screen. Looks cooler and easier to read while driving

 

Thank you. I guess I will give one a try.