38 mpg on Diesel, but they neglected to say how much CNG was being used.
Wow, that sounds like a meaningful figure.
Last I looked, Cummins had 6 cylinders that ran off of natural gas and that got over 5000 miles per gallon of Diesel fuel. I don't know how much natural gas they were running, but over 5000 MPG!
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1990 D-250 Regular Cab: Full power screw; stout TC and A518 w/ manual valve body; ratchet shifter; piston LP; Ramcharger tank; manual off; computer-programmable 40 GPH water/meth fumigation; gauges