Fuel Economy Advantage of 2-Speed Axles
Chapman, L., "Fuel Economy Advantage of 2-Speed Axles," SAE Technical Paper 831798, 1983,
data showing the fuel-saving capability of a two-speed versus a single speed axle
The two-speed axle with ratios straddling the ratio of the single speed provided substantial fuel savings when used as a transmission range extender at highway speeds.