Jane Powerson driving
It's a policy of mine never to criticise anyone's driving, except, of course, for my spouse's (which is fine, as he also subscribes to this system). For most people their driving is like their kids: exemplary - and you comment at your peril. One person's good driving is an energetic clip; for another it is a marvel of multitasking; for a third it is nothing less than a stately and careful advance along the tarmac.
But good driving, as far as the environment is concerned, is a horse of a different colour. In fact, to be cold-bloodedly logical about it, the only good driving is no driving. Every time we put a foot on the accelerator, the car is using up irreplaceable fossil fuels (unless it's running completely on biofuel) and emitting greenhouse gases and harmful fumes. So driving less is best: walk, cycle or take public transport if possible - and, if you must drive, combine missions such as shopping and recycling, and consider pooling cars if others are going in the same direction.
The way we drive can make a big difference to fuel consumption and emissions. Sudden braking, revving, rapid acceleration, speeding and generally behaving like a frustrated rally driver consumes 5 to 33 per cent more fuel, and produces more emissions, than more careful forms of using your car.
Each vehicle reaches its optimum fuel (and emissions) economy at different speeds, but 90km/h cruising speed in top gear is about average. For each 10km/h increase on that figure, fuel consumption goes up by about 10 per cent.
Underinflated tyres can reduce fuel efficiency and shorten their lives. Likewise, a car that is not running smoothly is more fuel-hungry, so keep the engine tuned.
Air conditioning gobbles up fuel (decreasing efficiency by
12 per cent), so open the windows if you're travelling at less than 70km/h. Open the back ones as well as the front, to allow the air to exit and to reduce drag. At more than 70km/h, wind resistance makes it more efficient to roll up the windows and turn on the air.
An obvious way to cut emissions and fuel use is to drive a small car. Trophy vehicles, such as huge SUVs and super-duper sports cars, are death to the planet. Behemoth Range Rovers, Porsche Cayennes and other off-road monsters emit two or three times more carbon dioxide than the cars we drove a few years ago - before we knew that we were heading for a collision with global warming. u planetmatters@irish-times.ie