That is interesting reading, a good job of documentation as well.

I think the mileage interest in that is Firebird specific.

I have a 51 Harley Panhead, a 68 Firebird and a 86 Ford F250 4X4. None gets good gas Mileage. I could sell it all and buy a Euro or Oriental car that gets very good mileage, or even an electric car. But I'd rather get poked in the eye with a stick.That's just me.

My GTO 400RA got six MPG, it was built to race.

When I build my 428 engine I had no choice on the bore as it needed to be bored 65 over to clean up the cylinders. I did have a choice with the shape and construction of the pistons, the stroke of the crank, type of lifters and rockers but most important: the camshaft. I could have built for high revving high horsepower engine but wanted more torque. I settled for a mere 535 HP but got almost 600 pounds of torque. Mostly due to the camshaft choice. So have 10.49:1 compression 463 cubic inch engine in a 68 Firebird coupe with a five speed manual, 373 rear 28 inch diameter rear tire and I get 26 miles to the gallon on the highway going way above the speed limit with the trunk completely full and two people on board. Could probably get a lot better at the speed limit but why would I have a 68 Firebird if I was going to travel at the speed limit. May as well take a bus.