US vehicle efficiency hardly changed since Model T

The average fuel efficiency of the US vehicle fleet has risen by just 3 miles per gallon since the days of the Ford Model T, and has barely shifted at all since 1991.

Those are the conclusions reached by Michael Sivak and Omer Tsimhoni at the University of Michigan Transportation Research Institute in Ann Arbor. They analysed the fuel efficiency of the entire US vehicle fleet of cars, motorcycles, trucks and buses from 1923 to 2006.

They found that from 1923 to 1935 fuel efficiency hovered around 14 mpg (5.95 km/l), but then fell gradually to a nadir of only 11.9 mpg (5.08 km/l) in 1973. By 1991, however, the efficiency of the total fleet had risen by 42 per cent on 1973 levels to 16.9 mpg (7.18 km/l), a compound annual rate of 2 per cent.

Progress has stalled since then, though, despite growing environmental concerns. From 1991 to 2006 the average efficiency improved by only 1.8 per cent to 17.2 mpg (7.31 km/l).

… If the country’s transportation fuel consumption is to fall by 10 per cent, Sivak and Tsimhoni calculate that the average fuel efficiency across the entire fleet will have to rise to 19.1 mpg (8.12 km/l).

New Scientist