Take, for an example, the newest SUV on the market, Audi's Q7. Like the A6 Avant estate, it can be bought with an excellent 3.0-litre, turbo diesel engine. But while the A6 reaches 62mph in 7.3sec and a top speed of 149mph, the Q7 needs 9.1sec and stops at 134mph. The A6 will return 34.9mpg and emit 229g/km of CO2; the Q7 a rather less impressive 26.9mpg and 282g/km of CO2. And why? In the main, because the Q7 weighs 520kg more than the A6. There are entire cars out there that weigh less than that.
For what? Well, as any SUV manufacturer will tell you, it's not for their almost invariably unused off-road ability. No, say their owners, it is because SUVs are so much safer than normal cars. Superficially, they have a point. It is indeed true that the more impact-absorbing material you can put between yourself and the site of an impact, assuming those materials are properly designed and positioned, the more protected you will be. Presuming you care not at all about what or who you hit - because if you did you'd never buy a large SUV - the problem with the above argument is it's only relevant when you're crashing.
Road safety experts always talk in terms of primary and secondary safety. Primary safety is a car's ability to avoid the accident in the first place. It is only when you do contact something hard that secondary safety comes into play. And if you believe that prevention is better than cure, surely you should drive a car that minimises the risk of you having a collision at all.
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| A6 Avant faster and cheaper to run than the Q7 |
Ah yes, say the owners, but SUVs do prevent accidents because they have four-wheel drive.
This argument withstands very little scrutiny. First, if the road is dry, which, even in Britain, it is most of the time, four-wheel drive offers no more grip at all. Even when wet, all four-wheel drive does is halve the traction burden of each tyre, meaning that, yes, when accelerating hard away from a wet roundabout, the car is less likely to skid. But how many accidents happen like that? In almost all dangerous situations the first thing the driver does is instinctively lift off the throttle, at which point and, like every other car on the road, there is no power being transmitted to any of the wheels.
