As fuel prices continue to rise across the country, many people are desperate for ways to save money on gas. Over the years, motorists, mechanics and other car enthusiasts have come up with a number of methods of purportedly improving a car's fuel efficiency.
Here is the truth behind some of the most popular gas-saving myths:
Myth: Keeping tires inflated above their recommended pressure will help maintain a car's optimum fuel consumption.
Fact: Every five pounds per square inch (psi) of tire pressure you lose can translate into a two per cent loss of gas mileage. You can usually find your recommended pressure on the inside of the driver's side door.
You may think that over-inflating your tires would save money on gas. In 2009, Popular Mechanicstested this premise by over-inflating the tires on a Honda Fit to 45 psi — 13 psi above the recommended pressure but five psi below the maximum.
On a drive from Los Angeles to Phoenix, the magazine's writers recorded a fuel consumption of 42.19 miles per gallon (5.575 litres per 100 kilometres). On the return trip, they inflated the tires to the recommended 32 psi, and the car's fuel consumption was nearly identical, at 42.14 mpg (5.581 L/100 km).
They noted that driving with over-inflated tires greatly reduced the car's handling and made for a bumpier ride. If you over-inflate your tires too much, i.e. above the maximum, there is also the risk a tire could burst.
Myth: Some car dealerships and garages have begun offering to fill a customer's tires with nitrogen gas instead of compressed air, with promises of increased performance and better fuel consumption.
Fact: According to Wheels.ca, this practice amounts to no more than a way for the garages to make a quick buck — the difference is negligible.
Nitrogen gas is used in commercial aircraft, high-performance race cars and some long-haul trucks because it is a pure gas, unlike air, which contains several different gases. That enables engineers to more precisely predict how it will react at high temperatures, which cause the gas inside the tires to expand and inflate the tires.
It's especially useful for airplanes because their tires undergo a lot of stress and temperature variations: from warm temperatures at take-off to freezing temperatures during flight and back to average temperatures prior to landing. When a plane lands, friction causes intense heat, which will affect each tire's pressure.
Filling your tires with nitrogen instead of compressed air has no bearing on fuel consumption, as long as they are properly inflated.
Myth: Many fluids, including gasoline, are denser at colder temperatures. Therefore, it would lead one to reason that filling up your car with gas in the wee hours of the morning, when it's cold, would give you more bang for your fuel buck.
Fact: The reality is service stations store their gasoline in underground fuel tanks, where the temperature is nearly constant all day and night. You may end up saving a penny or a fraction thereof by filing up in the morning, but any savings would be negligible.
Myth: The argument goes that even though running your car's air conditioning will reduce your gas mileage, it makes more sense to run the A/C on the highway because of the drag caused by opening your car's windows.
Fact: In 2011, Consumer Reports tested this theory and drove a Honda Accord on the highway at a speed of 105 km/h with the air conditioning on and reported that gas mileage was reduced. Driving the same car at the same speed but with no air conditioning and the windows down yielded no noticeable change in gas mileage.
Myth: The (misguided) idea behind this popular myth is that by shifting to neutral when driving downhill, you cut off the fuel supply to the car engine and it stops burning gas.
Fact: Modern fuel-injected cars continue to burn fuel when you take your foot off the gas pedal as only the fuel-delivery system shuts down. That's why idling your car laps up so much gas. Coasting in neutral down a hill, therefore, does not increase fuel economy because the car still uses gas. A better idea would be to coast in drive because constant shifting between gears, with an automatic transmission, could cause transmission shock.
Myth: The air filter in your car is designed to keep dust and dirt out of your motor in order to maintain performance, so keeping the filter clean will keep your motor running efficiently, right? Wrong.
Fact: Many of us change our air filters on the recommendation of a mechanic, usually when we get an oil change. However, modern air filters are actually designed to work more efficiently when dirty, using the dust and dirt as an added filter layer. A 2009 study conducted by the U.S. Department of Energy found that a dirty air filter had no effect on gas mileage in modern cars using fuel-injection technology. The study does say a dirty filter may result in acceleration difficulty and therefore shouldn't be left in place indefinitely. An air filter should be changed after about 48,000 km.
It starts with crude oil. Although Canada may produce more oil than it consumes, the country is at the mercy of global markets for the commodity. Increased Middle East instability, sparked by popular uprisings, has lead to concerns about supply. Better-than-expected economic growth, especially in developing nations such as China and India, has also increased demand. (AP Photo/Hasan Jamali)
The next link in the supply chain is refining. In order to turn thick, black crude oil into useful products such as gasoline, diesel, heating oil and jet fuel, it must be sent through a mind-boggling array of pipes and tanks, heaters and condensers to sort the components of the substance from lightest to heaviest. This is a complex and costly process, and is paid for by what is known as the "crack spread," or refining margin. This represents the difference between prices fetched for the products produced, and the cost of crude oil inputs.. (AP File Photo)
Once the oil has been refined into gasoline, it must be transported to retail outlets across the country. This is accomplished through a network of 23 terminals - from St. John's to Nanaimo, B.C. -- forming the backbone of the distribution network. (AP Photo/Jessica Hill)
The retail mark-up averaged 7.6 cents per litre in April. This national average masks wide variation, from lows of 4.6 cents in Calgary up to highs of 25.8 cents in Whitehorse, according to Kent Marketing Services, an industry consulting group. (AP Photo/Orlin Wagner)
Emily Corbett of Mechanicville, N.Y., pump gas at a station in Mechanicville, on Wednesday, May 11, 2011. New York, Indiana, Illinois and New Hampshire are among the first states talking about temporarily suspending part or all of the state and local taxes that can add 14 cents to nearly 50 cents to a gallon of gas. (AP Photo/Mike Groll)