2500km roadtrip in my 70 Duster

Did you try different metering rods ? you need to see how lean you can go and then go .002 thinner

I got my mpg from 9 to 11 with thicker rods. Doesn't sound like much but that is over 20% better. I think with 2.94 it could get 13 to 15 mpg..not sure what that is in liters. Yeah fuel cost like 2 times as much for road trips