Americans seem positively obsessed with automobile safety. In survey after survey, it consistently ranks at or near the top of the list of what people consider when shopping for a new car. If you are like most folks, you probably pore over pages and pages of ratings, statistics and features to find a car that gives you the best chance of surviving a crash.

But safety involves a lot more than cheating death. It involves escaping injury, too. And in that respect, one of the most important pieces of safety equipment in your vehicle often goes unnoticed or neglected--the head restraint. You seldom think about it when you get into the driver's seat, and you probably never checked it out when you bought your wheels.

In fact, head restraints represent your best defense against whiplash -- the broad term for a range of injuries incurred when an occupant's head and neck snap backward in a low- or moderate-speed rear-end collision. Though seldom life-threatening, it may involve back, neck or shoulder pain, headache, numbness, blurred vision, dizziness and various other serious symptoms.

According to the National Highway Traffic Safety Administration, more than 270,000 people suffer whiplash in rear-end collisions every year. Some experts dispute that figure, claiming the actual number of cases runs three to four times higher. Everyone agrees, however, that whiplash ranks as one of driving's most common perils. Every year, it costs the U.S. insurance industry more than $7 billion.

Height Counts

To best protect against whiplash, the head restraint should be at least as high as the top of the ear, advises Russ Raider of the Insurance Institute for Highway Safety, a safety organization that has done extensive research and testing on the issue. And it should be as close to the back of the head as possible.

Why is the distance between the restraint and the back of the head--what safety engineers call the backset -- so important A short distance allows less movement in a crash. In the milliseconds immediately after a vehicle hits your back bumper, the head appears to move backward. Actually, the torso -- nestled in the seat - accelerates forward with the energy of the collision; inertia causes the head to lag behind until the neck pulls it along. This applies extraordinary force to the neck--as much a 5 Gs at speeds as low as 5 mph. Ideally, the restraint should catch or support the head almost immediately, so that it accelerates along with the rest of the body.

At this point, the height of the restraint becomes critically important. If it doesn't extend above the head's center of gravity, the energy of the collision will force the head backward and over the top of the restraint, hyperextending the neck.

It used to be that unless you were short you'd have trouble finding a vehicle with head restraints that extended high enough to protect you, notes Adrian Lund, IIHS chief operating officer. Now automakers are making improvements so that in many vehicles even taller people can position the head restraints where they need to be.

Making Adjustments

Those improvements include more and more vehicles with adjustable head restraints for front-seat passengers. Many adjust up and down to accommodate the occupant's height, and some even move fore and aft to minimize the backset. But not all drivers take the trouble to actually adjust them. In a recent study, researchers observed more than 7,000 drivers in two cities on the Eastern Seaboard. Of the drivers who had adjustable head restraints, two out of three hadn't bothered to raise theirs. And of those, more than half had left theirs in the danger zone below ear level.

Recently, NHTSA took steps to improve the head restraint designs on all vehicles and protect taller occupants. Beginning with 2009 models, all vehicles must have front-seat head restraints that extend at least 29 12 inches from the hip, even if the driver doesn't raise them. (Current rules mandate adjustability only to 27 12 inches.) Also under the new rules, the backset must not exceed 2 inches. (Current Federal Motor Vehicle Safety Standards don't specify a maximum backset.) A few vehicles now on the market already meet the stricter standards, and automakers will begin phasing in new designs on some vehicles long before the '09 model year deadline.

Unfortunately, if the head restraint on your current car doesn't reach the top of your ears (either because it isn't adjustable at all or can't be raised high enough), there's not much you can do. Some aftermarket manufacturers offer retrofit devices that essentially increase the restraint height or decrease the backset, but IIHS's Raider notes that such add-ons haven't been tested.

One thing you can do, however Make sure that the head restraint on your next vehicle fits properly, whether you buy it new or used. IIHS offers ratings of 73 head restraint designs available on 63 vehicle models on the U.S. market. The ratings take into account not only the restraint's geometry (its height and backset) but also the performance of the seat and restraint together in simulated crashes. Check out the ratings yourself ( www.iihs.org) before you buy.