How does different fuels change mileage?



I keep seeing ads from fuel stations that say their fuels increase the mileage of the car but isnt the car doing all the fuel adjustments?Wouldnt it still pull the same amount of fuel from the gas tank?

In: Engineering

yea, its bullshit.

Base gasoline is set by the RON and Octane values, now some brands put cleaning agents, combustion assistants and stuff like that which can make your car run smoother and could cause a slight improvement in milage.

Premium fuel performance depends more on the compression of your engine, use the fuel specified in your car manual.

It doesn’t really, or at least not significantly. The energy content of gasoline is more or less the same no matter what brand you buy.

There are two factors that can have a small effect on the fuel consumption:

* Gas that contains bio-ethanol has slightly less energy than straight gasoline. So if the fuel contains no bio-ethanol, the fuel consumption will be slightly better.

* Gas with the wrong octane rating can make the engine computer change its ignition timing, causing the engine to run less efficiently, but that shouldn’t happen as long as you’re using the recommended fuel.

It’s true that the engine computer controls how much fuel is injected, but it does what your foot is telling it to do. So if the fuel contains less energy or the engine computer pulls ignition timing and the engine is making less power as a result, you will still want to go the same speed, so you will give it more throttle, which causes the computer to inject more fuel.

But really, it’s mostly just empty advertising promises.

When they say “improve mileage” I think that they actually mean the overall lifetime of the engine measured in miles, not the miles per gallon of gas that your car can go.

For instance, Chevron adds Techron to their gasoline, claiming that it keeps combustion deposits from building inside your engine. Those claims aren’t really backed by any real numbers or solid statistical studies.