Trip computer?

[Barry Tisdale]

I owned a Dodge Omni, early '80s carb version, which had an aftermarket trip computer installed.  It'd give you MPG, time to empty, miles & time to destination, etc.  Info needed by it was wheel rpm, time & fuel flow.  Flowmeter on fuel line to carb gave it that info.

Question:  are there any units available for FI engines, where a fuel flowmeter wouldn't be of much use?  Could you get *any* sort of accuracy calculating from rpm, bpw & throttle opening?  Maybe 2 flowmeters, one on supply rail, one on return line, subtract out from in?

Any thoughts from anyone?

Thanks - Barry