Of all the vehicles I own the 78' MGB gets by far the best MPGs. Getting on a good day about 30+ around town & even more on the highway. And that was before I pulled the old carb and went with EFI.
My 78' 928 with its 4.5L V8 gets the worst gas milage of them all. Heck it's even worse than my 01' full sized crewcab 4x4! The truck gets about 15-17 on the highway but I once drove it like an old maid - & even with the huge 5.4L V8 got about 21 mpgs.
The Porsche 928 I'd get better milage taking the same money paid for fuel at the pump and tossing it in a blender.
But still the MG beats them all. Its just impractical to use as my daily driver because of all the miles I clock each week.
Still thinking about paying off the truck and putting it into semi retirment & picking up a slightly used Mustang GT. Even with the V8 I should still get about 20plus on the highway.