Back in the 70s or 80s Emeco or ENCO made a device kind of like the MPGunio called a Add on “Driving Control System” travel mileage computer.
It worked by mounting two small magnets to your drive shaft, and mounting a small coil on an arm next to the shaft to produce an early version of VSS.
Then you placed in your fuel line near the carb the flow sensor.
Like the MPGunio once calibrated it then gave MPG, Miles left in tank, miles per hour, avg.MPG, MPG on Trip and perhaps a thing of more.
One great thing is as it makes its own signals it is unaffected by anything done to the cars computer and to the injectors. And there is a couple of features that the MPGunio does not do.
The main problem is the flow sensor was made to handle carb and early fuel injection pressures, which in a carb is under 5 PSI and in say TBI systems are under 20PSI.
My Fords with their Port injection run as high as 30/60PSI and higher.
So I fear fuel leaks from these old fuel flow sensors, and it has been reported the BB inside were out so I cannot expect a long life as well.
So thought I would once again look for better newer low cost flow sensors.
My cars are gasoline burning.
Here is a link to a picture of one:
https://www.facebook.com/photo?fbid=...30978023627450