Got an idea if u could monitor fuel return rate or fuel flow rate of the engine anyone have any idea on the flow rate @ max rpm/cruise? found some neat products under 200$ for 2-200gpm
https://shop.tuthill.com/Sotera/product_specific.asp?id=8

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2004 Infiniti G35 3.5L 6mt Coupe 73K miles 25.6mpg ytd
2001 Green Audi TT 225 AWD Roadster 71K 6sp 30.9mpg >>STOLEN<<
1982 300D Turbo 231K 120hp? 28.1mpg YTD

It becomes difficult on the MB diesels because you have the return lines coming off each injector. To be accurate, you'd have to measure two flows, going in to the injection pump and returning to the tank from the injector returns. Anyone who has tried to run without those return lines can tell you that the return flow is not insignificant.

Ken300D

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1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

Yes, for older diesels you'd have to measure both flows and subtract "return" from "supply." For the '96 and newer cars, something like the ScanGauge II will work (about $170, available on line, best price I've seen is from one of several eBay vendors). Google "ScanGauge," you'll get lots of hits. Also works as a tripmeter and a code scanner/resetter.

It will measure GPH as well as MPG and so forth, anything available from the car's computer. My '96 E300D uses about one quart of fuel per hour at idle, for example. I've never written down what the usage is at highway cruising speeds, a couple gallons an hour, I think. It's a fun toy, you can learn all sorts of things, some of which are even useful.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970