My '73 has a 904 with a 318 torque converter, 2.73 gears, 275/65/15 tires, a rebuilt '79 360 from a Volare wagon, a 650 Holley on an Offy intake, a semi-lumpy cam, a decent valve job, TTI headers with dual exhaust and an H-pipe, all the A/C stuff and power steering, and I drive like a lead-footed monkey - regularly cruise to Birmingham and back at 80-85mph... I get between 15 and 19 mpg whenever I check it.