[aerohead]

I dug out what I had on the Metro.
The ' 75 mpg Geo Metro' was based upon the Metro XFi, rated at EPA 53/58/55.
Popular Science Magazine achieved 59.9 mpg for the XFi on their economy loop.
Based on the OEM specifications and the late Douglas M. Heffron modifications, SAE metrics of the day, and allow Pop Sci's 59.9 mpg as the OEM benchmark for the XFi, then the ITworks supercomputing center at The University of Hard Knox estimates a potential 79.29 mpg for Mr. Heffron's car.
Had Suzuki been able to provide an exact 'gear-match' to ensure maintenance of the OEM BSFC, Mr. Heffron might have experienced the 79.29 mpg.
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CAR and DRIVER reported 84.1 mpg for the XFi, in 3rd-gear, @ 20 mph.
116.6 mpg, with pulse-and-glide, between 20-mph and 8-mph. At the Transportation Research Center, University of California at Davis, California.
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40 students, from 20-universities participated in the Geo Metro EconoRun in 1993. The Howard University came in at 1st-place, with an average 56.68-mpg, between San Francisco, California, and Manhattan, New York, along Interstate Highway-80.
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For cars of Cd 0.19, the 75 mpg Metro doesn't represent the most efficient shape, as compared to Boxfish, Impact, Ultralite, or M-B IAA, however the atmosphere is agnostic as far as CdA is concerned.