Q:I am going to buy my daughter a used SUV or car this fall. She is a teen driver and I want her to be as safe as possible. Can you please tell me whether it is safer for a vehicle to be high off the ground? My co-workers and family don't agree on this. - Barb L., Minneapolis
A:The reason the other people you have asked may not agree is that vehicle height has different effects and risks under different circumstances. In a straight-line collision on level ground, where the risk of a vehicle overturning is low, a high vehicle will ride up on a low one. If you're in an MG - a car I'll single out since I own one - and the vehicle you're striking is a large dump truck, the truck is going to ride up on the MG with potentially deadly results if the speeds are high enough.
Keep two things in mind about this scenario, however. First, government regulators and vehicle manufacturers have learned of the risks that apply here and are taking steps to get bumper heights more consistent across vehicles. (This is helpful not only for more serious collisions, but also for non-safety maneuvers, like parking, where bumper misalignment causes the high vehicle to hit bodywork or lights on a low one.)
As the years and injuries and fatalities have shown, high vehicles pose their own risks. Many young drivers and passengers have died in roll-over accidents since higher-riding vehicles came into vogue. A typical scenario is the SUV speeding along a country or suburban road with an embankment off either side. The youthful driver loses control, the vehicle slides off the roadside and with its high center of gravity, it rolls over. The vehicle roof, subjected to the heavy vehicle's own weight pushing down on it, collapses. Manufacturers have responded to this by making roofs less susceptible to collapse, but it's still a hazard depending on the speeds, the nature of the embankment and any obstacles, like trees or stumps, involved.
The most important consideration is the behavior of the youthful drivers and passengers themselves. Young people see themselves as having their whole lives - many decades - ahead of them. They neither understand nor fear death the way people who have lived longer and had a few brushes with it do. Youths not wearing seatbelts face a much higher risk of death in a collision than belted occupants.
The young people most likely to die in an accident are unbelted. If only they could all appreciate what happens to them in that event. Their bodies are moving through space at the same speed as the car or SUV. When a collision stops the vehicle, belted passengers strike their seatbelts, which distribute the force of the impact across broad sturdy portions of their torsos and waist. Unbelted passengers continue to move at the vehicle's speed until some other solid object brings them to a halt. It is these bodily collisions with glass and steel inside the vehicle that end so many lives.
The best way to preserve your teenager's life is to buy her a well-maintained vehicle with good brakes and tires and working seatbelts, and to impress upon her these essential and non-negotiable habits: always wear your own seatbelt and demand that all passengers wear theirs as a condition of riding. This is easy to enforce; don't start the engine until everyone is belted. Don't drink and drive and don't ride with anyone who has been drinking. Make a deal with your teenager to pick her up if she has been drinking; yes, she'll be in a little trouble afterward, but not nearly as much as if you learn she drove under the influence. Don't use the phone at the wheel; if you need to make a call, find a safe place to stop, take care of your call and then resume your drive.