Sorry to disappoint, but pumping your accelerator is not saving you any gas. It is the careful acceleration that is saving the gas. “Instantaneous” mileage is a relative term. With an engine turning at 2000 RPM, your crankshaft is rotating 33 times every second. In a six cylinder engine, that’s about 48 injector events per second. The flowmeter that is reporting to your instantaneous gauge isn’t trying to report in microseconds, but to show you the effects of rapid versus steady acceleration.
Pumping on your pedal has your mind on the wrong thing, and could interfere with your reaction time if you need to stop suddenly. I suggest that you quit doing that, it’s dangerous. Besides, it interferes with your texting, eating your hamburger, talking to the kids, and rubbernecking. Just drive normally and don’t accelerate too fast. If you want to experiment with gas mileage, do it on the highway by bumping up your cruise control a little at a time and taking note of the result. If you REALLY want to experiment, get a ScanGauge II and plug it into your OBD II port. This will not only give you instantaneous mileage, but will show you torque loads, ignition advance, fluid temperatures and so on. Then you’ll learn something about inertia, momentum, and other interesting physical principles.
While I have you all here, I want to suggest another experiment: After you’ve driven a ways on the highway, set the cruise control on a level stretch and note the MPG, or GPH of your instantaneous mileage. Then get off at an exit and buy some fuel with ethanol in it. Drive for thirty miles or so and watch in horror as your mileage drops by as much as 20% (assuming, of course, that you had regular grade gasoline in it before; if you had ethanol in it, reverse the process). Ethanol is being marketed to the environmentally conscious as a clean fuel that’s good for the environment. Nothing could be further from the truth. Ethanol contains 60% by volume of the energy in regular gasoline (look it up, 20,000 BTU vs 12,000). By the time you go the same distance with ethanol you will have burned 175% as much fuel. Which is why they only mix it with gasoline in small quantities, so that you are less likely to notice. Besides actually sending MORE CO2 into the atmosphere, you’re actually paying more for gasoline. If someone sold you a bottle of beer with 10% water in it, you’d probably complain—well maybe not, if they told you it had fewer calories, so it was better for you then and you could drink even more. But if you had any SENSE, you would complain. And no, it’s not a mistake that 10% ethanol will diminish your mileage by more than 10%. In the mid-range of torque where you drive your engine, it will take substantially more fuel to make it deliver the load. You will likely see it in your tachometer as well. Ethanol does burn slightly cleaner—in terms of pollutants— but as I said, the pollution has already been eliminated. When they’re talking about “cleaner”, that’s what they mean. Yes, I know Hot-rodders use alcohol fuels in dragsters, but that’s because they can radically increase compression without detonation. Fuel consumption doesn’t enter into their thinking at all since they’re only going a quarter of a mile.
The same people who fill your food with corn sugar and making you fat are now proposing to be your fuel supplier, driving up the price of food. Using food as a fuel is as environmentally irresponsible as you can be. If you REALLY care about the environment, REDUCE the amount of fuel you’re using. Saving energy through technology means reducing the waste side of the cycle—the exhaust, the traction, or the mechanical momentum. Gasoline engines are less than 30% efficient as it is, why make that worse by using watered down fuel? Work on the waste part of the cycle by re-using energy, such as using the engine as a brake in a manual transmission car (downshifting instead of braking), or by purchasing a hybrid, which uses the energy you accelerated with to slow you back down. Definitely buy turbocharged engines. Yes, they do use more fuel per cubic inch of displacement, but that’s because they produce more power, allowing you to buy a smaller engine in the first place. Don’t pump your accelerator, and your turbocharger will eventually bring your mileage back down.
In 2007, Transport Canada did a study on ethanol use and concluded that it actually causes higher emissions due to the higher consumption. We are NOT talking about pollution, by the way. CO2 is not a pollutant, but it IS a greenhouse gas. When we eliminated pollution from your emissions during the 1980’s—CO, SO2, NOX, something else had to replace those pollutants in the exhaust. An auto engine is an air pump that is literally sucking in tons of air to mix with a very small volume of gasoline (15 to 1 by volume, 350 to one by weight). Most of the air is nitrogen, so it doesn’t produce anything in the reaction. The oxygen combines with the carbon released when the hydrogen oxidizes and produces the power. You used to be able to commit suicide by locking yourself in the garage with the engine running, but that’s no longer true, because you’re engine is so clean burning (if it’s a newer that 1990 car and is not badly out of adjustment). So don’t bother. It will only add a headache to your other problems.