The 1997 Corvette was rated by the EPA for 18/25 mpg with an automatic transmission or 19/28 with a manual. Why so high? Because of both the light weight and a computer that forced the transmission to shift direct from first to fourth under certain circumstances. Thusly, the dreaded gas guzzler tax was avoided.
Starting in 1997, Corvette transmissions have had weird limitations in order to avoid the gas guzzler tax.