Quote:
Originally Posted by Old Tele man
Don't know how relevant it might be to *current* vehicles, but back in 1961-1967 a Ford Motor Company engineer came up with this logarithmic-form equation for estimating fuel consumption (161 car-sample):
c = K*(wt^0.3067)*(cid^0.3469)*(ar^0.3395); R^2 = 0.932
where:
c = gallons-per-mile
K = 5.248 x 10^-4
wt = weight in lbs.
cid = cubic-inch displacement
ar = axle ratio
• source: SAE Automotive Fuel Economy, Vol. 15 (PT-15), 1976, "Factors Affecting Vehicle Fuel Economy," by Clayton LaPointe, Ford Motor Company, page 105.
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Looks like a typical empirical equation. It should be close if you were to build a gas powered car with 60's technology... Changes in technology will alter the constants in the equation.
It comes out to 26mpg for my Civic, which is likely close if it were carbureted, had 60's aero, and were on crappy old tires.
You could probably generate a new version of one that would be more accurate. Or, likely a few of them to deal with different engine cycles (gas, diesel, hybrid) and aspiration (NA/turbo).