This ad appeared in Tales of Suspense #92. For only $5.95 you could save a bundle in gas costs. Was it true?
Back then you'd have to really poke around to figure out if it was worth the price, but today thanks to the wonders of the innertubes, I located a review of the product from Jim Dunne and Charles Bishop, back in the 1960s.
#1, get the car they tried all the products on; wow:
He installed the gadgets on our test car, a '68 Olds Cutlass S with a 310-horsepower, 350-cubic-inch V-8, four-speed manual transmission, 3.23:1 final drive ratio, and F70-14 tires. The engine was properly tuned and timed, and we never altered the settings.
Which should explain the baseline mileage and power numbers:
Gas mileage: 10.755 m.p.g. From 25 to 70 m.p.h.: 8.4 seconds.
That's right, under 11 miles per gallon. Ouch! But when they tested the GT Energy Chamber:
This unit is inserted in the gas line between the fuel pump and carburetor, where it is supposed to level out pressure waves in the fuel flow. The ads claim that it enables your engine "to extract more raw, blazing energy and more gasoline economy." The car ran normally in the consumption test but power flattened out at 60 in the acceleration test, with all the symptoms of fuel starvation.
Gas mileage was 10.9 m.p.g. From 25 to 70 m.p.h.: 9.6 seconds.
It got slightly better mileage, but at an obvious cost in terms of acceleration onto the highway. If we assume that gas was running about 35 cents a gallon back then, it would take you 13,000 miles to pay for the device. And the idea of going 30 days on a tank of gas... well, only if you'd previously been going about 29.875 days on that same tank.