Why mpg is a bad measure

All of this matters because you, the consumer, have been duped time and time again on fuel economy numbers. The dyno did not impart enough load on the car, and fuel economy was inflated. But what are other reasons why you might not be getting advertised fuel economy? They talk about driving style, vehicle condition, variations in fuel, and engine break-in.

All good points. Bad fuel, crazy driver, new engine equals low MPGs. A bad wheel bearing or dragging brake means higher road loads and low MPGs. Ambient conditions also affect fuel economy. Another variable is vehicle configuration. If you opted for the big wheels and the 4.

These are just a few of very many reasons why you might observe lower fuel economy than what you see on the sticker. Hopefully knowing how fuel economy is actually tested will help you, the consumer, understand the lengths automakers have to go to put those two big numbers on your window sticker.

He can be reached at at david. The gallons-per-mile system makes it easier to see that our efforts to reduce petroleum consumption and carbon emissions should focus on removing from the fleet the vehicles that have the poorest economy, even if we replace them with ones that only return moderately good economy.

Spending five or 10 thousand dollars to put a hybrid or diesel powerplant into a Honda Civic will save fuel. Now consider replacing a mpg Honda Civic with a mpg Civic Hybrid. One might think a whopping mpg bump in economy would save almost twice as much money compared to moving from the Taurus to the Focus.

Nothing to sneeze at, but shouldn't there be a bigger difference? And that's why PM is starting to report fuel economy this way on its test drives. Pointedly, the EPA should promote this system too. There, it's mostly liters per km. Here, it'd be gallons per miles. Do you know all this and just do the math in your head? Well, you're way ahead of the curve. Test yourself first, though Management professors Richard Larick and Jack Soll's experiments proved that consumers thought fuel consumption was cut at an even rate as mileage increased.

Most survey respondents said going from 34 to 50 mpg saved more gasoline over 10, miles than did moving from 18 to 28 mpg.

There are now a few moves toward putting consumption on window stickers, right next to mileage. That way, you could compare the Corolla's 3 gallons every miles against the Prius's 2, calculate the extra cost, and decide if you wanted to make that Prius statement after all. But, hey, Americans are stubborn. We beat back the metric system, right?

Consumption instead of mileage? Dumb idea. Never work. I agree to receive emails from Green Car Reports. I understand that I can unsubscribe at any time. Privacy Policy. The surge of the EV demand surprises even Tesla. Hertz opts to add at least , Teslas because of, in part, the experience and Supercharger network.

Apple and Tesla are both looking for the same kind of batteries. The Mercedes EQC is back on, albeit not for a few years. A misfire occurs when the fuel in an engine cylinder does not combust. Since unburnt fuel cannot power your vehicle, this ends up wasting gas and lowering your fuel economy. You may experience rough idling, stumbling, or an overall decrease in power from the engine if the ignition system is to blame.

The most common culprit inside a failing ignition system is the spark plugs. The thinking goes that since internal seals and gaskets become brittle and shrink with age, thicker oil would be less likely to seep through the cracks. In addition, the viscosity is slightly increased to help worn piston rings seal better.

However, thicker oil actually creates more resistance between engine parts, which lowers fuel efficiency. The right motor oil is essential to keeping modern engines lubricated and protected. High mileage engine oils may help reduce oil leaking and oil consumption but it will take away some of the potential fuel efficiency. Mass airflow sensors measure the amount of air flowing into the engine. Like an oxygen sensor, the mass airflow sensor sends data to the onboard computer to calculate the correct air-to-fuel ratio in the engine and the computer adjusts fuel injection accordingly.

Mass airflow sensors should be cleaned with a special cleaning spray. Low-pressure tires are a common cause of worsening MPG because an underinflated tire has increased rolling resistance with the road and a slightly smaller effective diameter.

Modern cars come with a tire pressure monitoring system TPMS to notify drivers when their tires need more pressure, but the warning is only triggered after a significant loss of PSI. One of the easiest things you can do to keep up fuel efficiency is to regularly check your tire pressure and top-up with air as needed.

Another smart option is to use Bridgestone Ecopia tires , which are made with fuel economy in mind. Ecopia tires feature a low rolling resistance tread designed to help you save both money and fuel with fewer trips to the gas pump. Not only is it dangerous to drive with worn-out brake parts , but sticky brakes could also be causing your MPG to plummet.