I think this data vindicates my approach of low RPM = max MPG, even for gasoline engines. The Z06 with its LS7 engine has such mammoth torque as to allow operation at vividly low RPMs. The same principle works for a high-revving Honda engine, just the cutoff for lugging occurs at a higher RPM.
As you can see from this, the Tremec 6060 transmission used in the Z06 has a 0.63:1 top overdrive ratio, but a 0.5:1 ratio could be had if MPG were to be emphasized.
Tremec TR-6060 transmission - Wikipedia, the free encyclopedia
BTW, I am seriously looking at getting the Challenger version to replace the ZF6-650 in my truck. That with a couple of aero tweaks might get me over 30 MPG in my mixed-driving circuit. It has an optimal ratio spread and its 600 ft-lb rating is A-OK for my Powerstroke which has been dyno-tested to deliver 560 ft-lb max torque. Having a 1.54:1 overall reduction should give spectacular results.
Too bad the GM 4.5 liter diesel is dead. Given the LS7 in this test is operating way below its peak volumetric efficiency, it is incurring huge pumping losses for not much power. The diesel suffers no such loss. It would be interesting to see what a 4.5 could have done if fed the 70 cetane Fischer-Tropsch fuel the Audi & Peugeot prototype racers use.