Planet matters

Jane Powers on car size.

Jane Powerson car size.

We all know the common arguments for smaller cars: less fossil fuel consumption and less greenhouse gas emissions. But just to remind you, let's compare two cars. The first is the one that - according to the Society of the Irish Motor Industry - makes the least environmental impact: the one-litre Daihatsu Charade. The second is a a major-league guzzler and emitter: the four-litre Range Rover. I won't bore you with the figures, but the larger car uses about three times as much fuel, and emits three times as much CO2.

But let's leave fuel and emissions aside, and park them here for the rest of this article. Instead, let's look at size, and see if it matters. The Charade is 3.4m long, while the Range Rover is 3cm shy of five metres. The smaller automobile weighs 740kg, and the larger is 2,687kg. Two and two-third tons of metal, rubber and other materials is an awful lot of "stuff" (compared with three-quarters of a ton). It all has to come out of the Earth, and when the vehicle's life is over, it has to be dismantled and put somewhere. And because there is a greater volume of material, the making and decommissioning processes are more energy-intensive. Therefore, the smaller car wins environmental points on weight and volume.

The smaller car also wins on length and width: you can park more of them in a row, or side by side. Smaller car gets there faster, too. You can fit more small cars on the road than you can large ones (the Charade is only 70 per cent of the length and width of the Range Rover); and because they're nippier and can manoeuvre into tighter spaces, they get there more quickly. Imagine how expeditiously the traffic would move if everyone drove tiny cars.

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But surely smaller cars aren't safe, and the larger your vehicle the safer you are? Actually, no. Statistics compiled by the Lawrence Berkeley National Laboratory in California and the department of physics at the University of Michigan show that the safest cars in the United States are small(ish) imports. Among those that are involved in the fewest fatal accidents are the Honda Accord, Toyota Camry, and Volkswagen Jetta.

One of the reasons for this is driver behaviour. Owners of small cars tend to drive more defensively: they're closer to the road and respond more readily to its challenges (and, being in more nimble cars, they have a better chance of staying out of trouble). Large cars, especially high-up SUVs, can make their drivers feel more insulated and dominant, so that they drive more aggressively. But a larger car, especially a heavy 4x4, is less responsive, takes longer to stop, and is more likely to be skewed by its weight. The vehicle that feels safer isn't necessarily so. Often, the safer a driver feels, the less safely he or she drives. But when you think of it, being in charge of a ton or two of metal, no matter how well padded, is a hazardous business - and requires some serious attention.

There's another reason for driving a small car. They're incredibly cool. And macho. One of the biggest, baddest men in the recent rugby World Cup, France's Sébastien Chabal ("the Anaesthetist") drives the smallest car on the road: a Smart car (all 2.69m of it). planetmatters@irish-times.ie