Six Fuel Saving Myths

Based on a recent article in CNNMoney.com, adapted here are 6 fuel saving myths that people think will save money at the pump. With fuel prices hitting record levels, I can see why some people try these but are unlikely to save much. Do you know of any more?

Myth #1. Filling your tank in the morning

You may have heard that it's best to fill your fuel tank in the early morning while the fuel is cold. The theory goes that fluids are more dense at lower temperatures, so a litre of cold fuel actually has more fuel molecules than a litre of warmer fuel. But the temperature of the fuel as it comes out of the nozzle varies little during the course of the day, according to Consumer Reports, so there's little, if any, benefit, to getting up early to pump fuel.

Myth #2. Change your air filter

Maintaining your car is important, but a clean air filter isn't going to save you any fuel. Modern engines have computer sensors that automatically adjust the fuel-air mixture as an increasingly clogged air filter chokes off the engine's air supply. While engine power will decrease slightly as the air filter becomes clogged, a lack of performance or an increase in fuel consumption will be negligible, Consumer Reports says.

Myth #3. Use premium fuel (I do this - will change to regular now!!)

With prices approaching $2.00 a litre, premium fuel is a hard sell these days. But a lot of drivers think because their owners' manual recommends premium, they'll get better fuel economy if they stick with it. Really, they're paying more money for nothing. Even cars for which premium is recommended won't suffer with regular fuel. Modern engine technology comes to the rescue again. When sensors detect regular instead of premium fuel, the system automatically adjusts spark plug timing. The result is a slight reduction in peak horsepower - really, you'll never notice - but no reduction in fuel economy.

Myth #4. Pump up your tires

Proper tire inflation is important for a number of reasons. Under-inflated tires are bad for handling and can even cause a crash. Improper tire inflation also causes tires to wear out faster and to heat up more, which could trigger a dangerous high-speed blow-out. Under inflated tires reduce fuel economy, so proper inflation is key. But you should never over-inflate your tires. They'll get you slightly better fuel economy because there will be less tread touching the road, reducing friction. But that means less grip for braking and turning. The added risk of a crash isn't worth the extra mile a litre you might gain.

Myth #5. To A/C or not A/C

There's no question air-conditioning makes extra work for the engine, increasing fuel use. But car air conditioners are much more efficient today than they used to be. In around-town driving, using the A/C will drop fuel economy only marginally. Meanwhile, driving at higher speeds with the windows down greatly increases aerodynamic drag. As speed increases, drag becomes more of an issue, making A/C use the more efficient choice at high speeds.

At most speeds and in most vehicles, A/C use drains slightly more fuel than driving with the windows down. The best choice - if temperature and humidity allow - is to keep the windows rolled up and to turn the A/C compressor off. You can keep the fans running to blow in air from the outside, but your car will be as aerodynamic as possible while still letting you breathe. You will save fuel, but the fuel economy improvement will be slight.

Myth #6. Bolt-ons and pour-ins

Before you buy a device that's supposed to make your car more fuel-efficient or pour in an allegedly fuel-saving additive, ask yourself this: Don't you think oil and car companies aren't doing everything they can to beat their competitors? If Shell could add something to its fueloline that made cars go farther on a litre, cars would be lining up at the company's fuel stations. Sure, people would burn their fuel-saving BP fuel more slowly, but then they'd drive right past rivals' fuel stations to come back to Shell for more. Shell stations could even charge more for their fuel and still sell tons of the stuff.

So if there really was an additive that made fuel burn up more slowly, it wouldn't be sold over the Internet one bottle at a time. Likewise, car companies are already spending big bucks to increase fuel mileage. If Holden (owned by General Motors) could make its cars go significantly farther on a litre simply by putting a device into the fuel line, don't think for a second it wouldn't be doing that. Holden's car sales would go through the roof.

But drivers who try them will swear they work. In reality, it's probably an automotive placebo effect, says Reed. Buy one of these devices or additives, and you're like to pay extreme attention to your fuel economy and how you drive. Of course it can't hurt to keep a close eye on your driving habits -- and what kind of car you drive. In the end, that can make the most difference in saving fuel.