Petrol prices keep rising and falling, usually stabilizing at higher levels. There's not much you can do about that, but there are several easy and inexpensive things you can do to your vehicle to get the maximum kilometres per litre, adding up to considerable savings over a full year of driving.

There are three areas to consider when trying to attain or beat the EPA kilometre claims for your vehicle—reducing parasitic losses, maximizing engine efficiency and changing your driving style. Don't look to any single item for a massive mileage increase. It's a game that requires discipline to find many small improvements that will add up to possibly a 10-15 percent overall increase in fuel economy.

What are the parasitic losses that affect fuel mileage? Anything that impedes the movement of the vehicle down the road such as (tire) rolling resistance, wind resistance, brake drag, wheel alignment and driveline friction. Some items like wind resistance are difficult to avoid. However, tire rolling resistance, brake drag, wheel alignment and driveline friction can all be optimized for a sizeable gain in mileage.

Tyre Pressure

The first place to start any mileage self-help program is to purchase a tire gauge, keep it handy, and use it often. Most vehicle manufacturers recommend tire inflation pressures that are a compromise of comfort and safety. In the vehicles owners manual are listed a range of tire inflation pressures usually to compensate for loaded and unloaded conditions. One of the most important changes you can make is to keep your tires inflated at the highest recommended level. If the manual gives only a single inflation pressure, read the information on the sidewall of your tires concerning maximum safe inflation pressure and add 3-5 pounds of air making certain not to exceed the stated maximum inflation pressure noted on the tire. Keep a close eye on your tires for uneven tire wear. Greater tread wear in the center means too much pressure. If this happens, rotate the tires and slightly reduce air pressure.

Brakes & Alignment

Most brakes drag, but how much is too much? This varies from vehicle to vehicle and it's best left up to an expert at a brake or tire shop to decide, but the good news is that the inspections are usually free. Typical problems are calipers that are not fully retracting because they need to be replaced or rebuilt, or drum brakes that are incorrectly adjusted. While you're there, have the wheel alignment checked and aligned if needed. A modern car typically requires 10-20 road horsepower to maintain a cruise speed on level ground. Improper wheel alignment, a dragging brake or tire pressure that is too low could double the required road horsepower, cutting fuel economy by as much as 20 percent.

Synthetic Lubricants

So far the items we've talked about are free or are service procedures that you would perform to keep your car safe and operating properly. However, reducing driveline friction is going to require an investment above normal maintenance. The best way to reduce mechanical friction in the drivetrain is to replace petroleum-based lubricants with more expensive synthetic lubricants that have been proven to greatly reduce parasitic drag in engines and differentials. Several NASCAR teams have used zero-weight synthetic oils in their qualifying engines for years because of the horsepower it frees up. Expect to pay up to four times as much for synthetic as petroleum lubricants, however, you get some of that back in longer oil change intervals and longer engine life and easier cold weather starting. This is an area where you really have to do the math and decide if synthetics make sense for you.

Fuel System

Engine efficiency is as critical to fuel economy as reducing parasitic losses. Today's modern computer-controlled, electronically fuel injected engines do a great job at monitoring and adjusting fuel/air ratios for maximum performance and efficiency, but there are still a few things we can do to optimize their performance. Several items need to be regularly serviced. Keeping the air cleaner clean or upgrading to a lower restriction filter element will prevent the choking (richer fuel mixture) effect. Adding fuel injector cleaner to the gas tank every 10,000 kilometres will ensure that the injectors properly atomize the fuel for consistent combustion and efficiency. Another overlooked component in the fuel injection system is the oxygen (O2) sensor. It is really the brain that tells the computer how much fuel to send to the engine. Replace every 80,000 - 100,000 kilometres to keep your engine running at peak efficiency.

Tune-Ups

Naturally, regular tune-ups that include maintenance of the ignition system and emissions system are very important, but some parts are often overlooked. Engine misfires in today's engines are usually caused by of one of two items: plugged fuel injectors or bad spark plug wires. Misfires take a toll on performance and mileage, no matter how slight. It's a good idea to replace spark plug wires every 80,000 - 100,000 kilometres, depending on how severe your driving conditions are.

Driving for Kilometres

Nothing you do mechanically will have as much effect on fuel mileage as the way you drive. Acceleration requires more horsepower and additional fuel, so how hard and how fast you accelerate determines how much fuel you'll burn. The key is to accelerate smoothly and evenly, staying with traffic, and look ahead so you can anticipate when you will need more power to climb a grade so that you can slowly increase your speed. World famous race driver Jackie Stewart described it best as driving as if there was an egg under the gas pedal.

Another driver-controlled item that has a big influence on mileage is the air conditioning. Air conditioning is one of those parasitic losses that can be eliminated by simply turning off a switch. This is a big one—usually worth 1-2 kpl. Turn on the vents and crack the windows for a huge fuel saving.

We've covered most of what makes sense in the quest for better fuel mileage. There are other major changes such as special gear ratios and torque converters that may provide even larger fuel economy improvements. But when you pencil out the total cost involved, you would have to own the vehicle for 10-15 years to see a return on your investment. A better plan is to trade your vehicle in on a newer, more fuel-efficient model.

Petrol-Stretching Strategies
How to get the most kilometres out of each tank

While prices at the pump are escalating to record heights, most motorists are getting less out of a tank of gas. Average fuel economy for 2001 model-year cars and light trucks is 14 km per litre, the worst since 1980 according to the Transportation Department.

The Energy Information Admin, which surveys 800 service stations nationwide, reports that the cost of regular unleaded gas is up 22 cents from last year. The department forecasts that the national petrol price could climb to more than $1.20 a litre this winter—and some parts of the country could see prices hit $1.50 a litre.

Kilometre Mastering

There are ways to stretch a tank of fuel, but it means altering driving habits and keeping an eye on maintenance. A few alterations to normal driving techniques can squeeze as much as 10% more out of a tank of fuel.

On the highway, more than 50% of the energy required to keep rolling is aimed at overcoming aerodynamic drag. As the pedal hits the metal, the aerodynamic drag and rolling resistance increase. That's why the 110 kmph speed limit was clamped on the highways in the 'late 70s. Above 110 kmph, fuel economy takes a dive. So by cutting highway cruising speeds to 110 kmph instead of 120 kmph, fuel is conserved. When you use overdrive gearing, the engine speed decreases, reducing both fuel consumption and engine wear. On the open highway, utilizing cruise control maintains a constant speed and can also help reduce fuel consumption.

Nearly 50% of the energy needed to power a car goes into acceleration. A pattern of "rabbiting" through traffic with sudden stops and squealing accelerations wastes a lot of fuel. Eliminating tailgating from driving habits and the resulting unnecessary braking and acceleration can improve fuel economy by 5% to 10% and reduces wear on tyres and brakes.

Tips

Here are some other fuel saving tips from the Alliance to Save Energy, a coalition of business, government, environmental, and consumer groups:

> Keep tires properly inflated. Low tire pressure reduces fuel kilometres and causes increased tread wear. You can lose up to 6% of fuel efficiency for every pound per square inch (psi) below the manufacturer's minimum recommendation.

> Turn off your engine if you are stopping for more than 30 seconds. Restarting your car takes less fuel than idling.

> Remove unused luggage, bicycle or ski racks and other extra weight you may have in your car. Every 200 pounds of unnecessary weight reduces mileage by one km per litre. (Yet another reason to go on that diet!)

> Have your tires properly balanced and keep the vehicle "in alignment" to get the best fuel mileage.

> Plan your trip before you leave. Getting lost or having to backtrack wastes fuel and frays tempers.

> Service your vehicle regularly. Keeping a vehicle well maintained keeps it operating efficiently and reduces fuel usage. Replace air filters and fuel filters regularly. A new oxygen sensor alone can improve fuel mileage by as much as 15%.

> Turn off the air conditioner whenever you can. Running you're A/C causes extra work for the engine, which lowers fuel efficiency by 5-10%.

Saving Gas in a Crunch
Volatile fuel prices call for fine-tuning driving habits

During the last fuel crisis in the Persian Gulf in the 1970s, Australian motorists could only squeeze 14 km out of a litre of fuel, however, that litre only cost 45 cents. Today, fuel prices have spiked to more than one dollar fourty a litre in some areas of the country—and light trucks, the most popular selling vehicles, are thirsty vehicles. A barrel of crude oil hit $40 before Iraq 2, but slipped back down to $30 the day before the second Gulf War was launched.

History

In 1970 there were seven major oil companies that held the concessions for oil production in the Persian Gulf. Now there are four. Leaner and meaner corporate management has led these companies, Exxon Mobil, Chevron Texaco, Royal Dutch/Shell Group and BP, to cut their crude oil inventories by 115 million barrels. After the economic downturn following 9/11, OPEC cut production and the Bush administration began buying oil for the nation's Strategic Petroleum Reserve. Oil prices began to drop and consequently U.S. producers let inventories drop. That, in turn, led to price spikes in oil and fuel. As the buildup to the war with Iraq began, oil prices began to rise in September 2003. A hurricane in the Gulf of Mexico hurt oil production in October 2004 further squeezing inventories. A December 2004 strike in Venezuela, where the U.S. gets a good deal of its crude oil, further shortened supply. If Iraq ever fires its oil fields, less crude oil will make it to market. All this sets the stage for volatile pricing at the pumps. Australian motorists may be in for price rises at the pumps as shrinking supplies lead into the autmum and winter driving periods.

Tips

Getting more out of a tank of fuel will have an economic thrust for Australian drivers if prices at the pumps keep going up. Motorists can add 25 percent to the life of a tank of fuel with a few simple adjustments to driving habits and auto maintenance.

> Underinflated tyres can cut fuel economy by up to two percent per pound of missing pressure.

Check your tyre pressure at least once a month. Worn spark plugs and dirty air filters also increase your vehicle's thirst.

> Carrying a heavy load of unnecessary items in the trunk can increase the fuel needed for daily trips.

> Slowing down the pace of driving can slow down the drain on fuel. Rabbiting through traffic will deplete a tank of gas much faster than a steady pace.

> On long trips use cruise control. A steady pace uses less gas. Look at your personal fleet and use the most fuel-efficient vehicle for the majority of your driving. Go a step further and consolidate small trips into one by shopping ahead online or through newspaper and magazine ads to pinpoint your shopping destinations.

> When you are looking for deals on fuel, remember that you can save almost 5cents a litre by filling up at the self-serve rather than the full service pump.

Don't feed your car mid-grade or premium gas unless it is recommended in your owner's manual or to prevent knocking in an older vehicle.

> When caught in heavy traffic, don't let your engine idle for more than a minute.

Idling consumes half-a-litre to one litre of fuel per hour and wastes more fuel than restarting the engine.

> If your car is parked in the sun, roll the windows down and let the hot air escape during the first few minutes of driving before you turn on the air conditioner.

> Periodically calculate the vehicle's fuel economy performance. A loss of fuel economy could mean mechanical trouble.