SUVs: Bigger is not always better

The Tiger Woods crash this week – where the 45 year old suffered “serious leg injuries” after his Genesis GV80 (Hyundai’s upmarket brand) SUV rolled over and crashed in California – is yet another warning about the inherent dangers in many of these vehicles … even the most up-to-date models.

The harsh truth – which many manufacturers coyly avoid and salespeople will never mention to you in the showroom – is that these vehicles are at a higher risk of a rollover than an ordinary sedan or hatchback car. And that’s because of a simple principle of physics: centre of gravity. Scientifically, this is defined as the point at which the weight of an object is evenly dispersed and all sides are in balance. In the case of most SUVs, this is higher than in sedans and hatchbacks, because the SUV stands taller, mainly thanks to its raised ground clearance.

Graphics: Costa Mokola

A tall object – like an SUV, van or truck – is likely to be more easily disturbed by the sudden application of additional forces than is a normal vehicle. That has been known for years … and until about 40 years ago, that wasn’t much of a problem, because SUVs particularly couldn’t really go fast enough to get themselves into trouble. However, the global market for SUVs has mushroomed and many of them have become fast vehicles in their own right.

The SUV Tiger Woods was driving is capable of a top speed in excess of 200 km/h and acceleration on a par with a decent sports car of 20 years ago. The problem is that when power and speed meet a sudden emergency manoeuvre – avoiding a pedestrian or animal, or a pothole, for example – then the already high centre of gravity of an SUV can be disturbed to the extent that the tyres can no longer support the weight.  The vehicle then either falls on its side or, if the velocity is high enough, rolls over.

Graphics: Costa Mokola

That is why, “in the old days” drivers of tall offroad vehicles never travelled too fast, even in the unlikely event they had the power to do so. Today, many SUVs (as well as double cab bakkies) do have the power and speed. But generally, because of their size and centre of gravity limitations, as well as compromise on off-road tyres, their braking performance is not as good as equivalent sedans.

Some manufacturers warn owners about the dangers of a rollover.  Toyota, along with Land Rover, as well as Asian carmakers, do – but how many drivers bother to read the handbook? It is true that a bigger vehicle comes off better against a small one in a collision but the myth about SUVs being safe is just that… In the US, 70% of all rollover accidents involve SUVs, despite the vast improvements in safety systems across all vehicle categories in the past decade. And when occupants don’t wear their seatbelts (Woods was wearing his), the results are often tragic.

Graphics: Costa Mokola

There are two examples close to home about how dangerous can SUV can be. In April 2006, R&B star Ashanti Douglas had to pull out of a concert in Johannesburg when her cousin was killed in a car crash in Randburg. Quinshae Snead, 20, was flung from a BMW X5 when it rolled after being rear-ended by a speeding Toyota Corolla.

She was thrown into the oncoming lane and hit by another vehicle. Had the BMW been a 5 Series, the Corolla would
merely have smashed into it, instead of going underneath and flipping it over. In October 2006, local singing sensation Lebo Mathosa died after her driver lost control of her Toyota Prado on the N3. The Prado was the short-wheel-base model, which would be even more vulnerable to a rollover in highspeed avoidance manoeuvres.

Moral of the story: buy an SUV if you must, but be aware of its shortcomings. Get some training about driving in emergency situations, too.

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