71GMC 3/4 402, 4spd, 3.54 gear 11.5 all the time. Highway, city, loaded, unloaded. That was with a holley 650 dp. Just switched to an Edelbrock 750 so we'll see if that changes anything
00 Jimmy/Envoy 18.6 per the computer. Averaged 22 on a trip up to Banff with a plastic bucket on the roof (for the camping gear).
99 Regal GS (supercharged) 22 around town.
83 Capri 5.0 (yes a F%rd). 4spd, holley, don't know what gear. 17
62 Impala 235, 3 on the tree. Would you beleive only 10.5!!!? Little motor is working real hard to keep up at 70-75.
Had a 97 Cutlass with the 3.1. Around town it was about 23. That car was amazing on the highway. On a trip to Idaho we averaged 34.5. Got rid of it when the intake gaskets started to leak (learned about Dexron the hard way). Froth in the oil made my decision for me.