Tips on how to cut your gas usage

1. Low-carbon motoring
Even if your vehicle's a gas-guzzler, the following tips could cut its fuel usage by as much as 30 per cent. Some of them are now incorporated in the tests that new drivers take in the UK, the Netherlands and several other countries.

2. Drive at the right speed
Most cars, including hybrids, are most efficient when travelling at speeds in the range of around 45 to 80 kph (30 to 50 mph). As speeds edge above 90 kph (55 mph), cars gulp an increasing amount of fuel to travel the same distance -- as much as 15 per cent more for each additional 16 kph (10 mph).

3. Lighten the load
Keep heavy items out of your car unless you need them -- you'll typically lose one or two per cent in efficiency for every 45 kg (100 lb) you haul. While you're at it, check the tire pressure often: rolling resistance goes up and efficiency goes down by as much as one per cent for every PSI (pound per square inch) below the recommended pressure range. However, there's no benefit, and some risk, to driving with over-inflated tires.

4. Avoid idling
Except when it's required (such as in stop-and-go traffic), idling is a needless and wasteful practice, and it doesn't benefit your car, except perhaps in extremely cold conditions. Even five minutes of idling can throw half a kilo (1.1 lb) of greenhouse gas into the air. Anything more than about 10 seconds of idling generates more global-warming pollution than stopping and restarting would.

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5.  Use the air-con sparingly
As you'd expect, air-conditioning normally saps energy and cuts down on vehicle efficiency by a few per cent. However, if you're on a long road trip and it's a choice between driving with the windows down and running the A/C, there may be little difference in fuel usage, according to some studies.

That's because wide-open windows can increase the car's aerodynamic drag, especially at high speeds. If outside temperatures are comfortable, try using the vents and fan but leaving the A/C off.

6.Starting and stopping
Jack-rabbit starts and stops not only put wear and tear on your car, but they also drain fuel economy.

Accelerate gradually, and anticipate stops by starting to brake well in advance. If you have a manual transmission, the best time to change gears is between 1500 and 2500 rpm.

The rules are a bit different for hybrids, which has led to some confusion.

In 2005, The New York Times and Consumer Reports magazine declared that hybrids fall far short of their advertised miles per gallon. However, according to energy expert Amory Lovins of the Rocky Mountain Institute, this is because the tests employed by both publications didn't take into account the different driving style needed for hybrids, which typically call on the electric motor at low speeds and the gasoline engine at high speeds.

With a standard engine, you're better off accelerating lightly no matter what the speed. In a hybrid, you should accelerate briskly until you get to the optimal in-between speed, around 45 to 60 kph (30 to 40 mph), where the car is at its most efficient. A technique called "pulse and glide" driving -- basically hovering in that optimal speed range through small accelerations and decelerations -- can boost your hybrid's efficiency.

When it's time to slow down, brake slowly at first, then increase the pressure: this ensures that the maximum energy goes into charging the battery versus creating unusable heat in the brakes themselves.

Looking for extra ways to save? Discover 10 things you're wasting your money on here.

Excerpted from The Rough Guide to Climate Change (1st edition) by Robert Henson, published by Rough Guides Ltd. Copyright 2006 by Rough Guides Ltd. All rights reserved. No part of this excerpt may be reproduced except with permission in writing from the publisher.

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