What You Need to Know About Passenger Cars and Safety

Editor's Note: Luxury vehicles and sports cars are addressed on the safety page of their respective Buying Guides. This page is dedicated to more modest cars and wagons in the small, midsize and full-size categories.

We avoid deeming a vehicle "safer" than another because there are innumerable unquantifiable factors that contribute to a vehicle's overall safety. The passenger-car category is a broad one, so it accounts for many makes and models and many owner types and driving styles. Fatality histories reflect luxury cars as being safer as a class because luxury owners tend to be more careful drivers. For the objective read we turn to crash tests.

Top Crash-Test Scores

The nine vehicles above represent the top scorers in the Insurance Institute for Highway Safety's passenger car crash-test rankings. For Small Cars and Large Family Cars, frontal and rear tests factor in. The Midsize Inexpensive Cars rating adds the side-impact test results. Weight differences between these classes make comparisons invalid.

The IIHS's dynamic seat and head restraint test uses a sled that mimics the forces that occur when a stationary vehicle is rear-ended by a similarly sized vehicle traveling 20 mph.

The number of cars that score Good overall, some with the added Best Pick designation, is higher than ever. This reflects manufacturers' efforts to comply with requirements and improve their vehicles' safety. Because crashworthiness depends largely on the vehicle's underlying structure, the most significant jumps in performance appear on the all-new and recently re-engineered models. It's clear from the early ratings that head-restraint and seat design will be the next area of focus for automakers, as most tested models rated Poor in the rear impact (see tips below on how to judge head restraints).

Passenger Car Pros and Cons

As a class, cars and wagons' main advantages over light trucks is their lower center of gravity, their size and their braking. Their lower center of gravity translates to a lower likelihood of rollover. While a car that goes off the pavement can roll, its lower center of gravity makes it less likely to do so than pickup trucks or sport utility vehicles, which are more easily "tripped" by a curb or soft shoulder. Cars' lower center of gravity also makes them more nimble and capable of avoiding a collision, as do their smaller size and typically shorter braking distances.

Unfortunately, a couple of the car's advantages are also its disadvantages: The lesser weight and lower height make them vulnerable to heavier, higher vehicles. Historically, pickups and truck-based SUVs have not been as meticulously designed to absorb crash energy, but their weight and height make up for it in crashes with lighter vehicles, whose occupants pay the price.

Aside from the weight issue, it's a matter of compatibility: A high truck can ride up over the most robust part of a car's frame structure, bypassing its crumple zone and plowing into its cabin. Automakers have only just begun to make their trucks more compatible with car safety structures, and most cars are even less prepared. Buyers who are concerned about this should consider one of the higher-riding cars or "crossover" vehicles that increase the chance of compatibility in a crash.

When side curtain-type airbags deploy, they provide a layer of protection between an occupant's upper body and the intruding object.

A side impact from a truck or SUV is perhaps the greatest danger. There are just inches and practically no steel between a truck bumper and a car occupant's upper body. This is why side-impact airbags are a must, as discussed below. Features can't compensate for weight and height differences, but they can certainly help.

Features to Look For

ABS and disc brakes: Antilock braking systems, increasingly a standard feature, are well worth having. They shorten stopping distances in some situations, but their main benefit is that they allow the driver to steer even when applying maximum braking. Though drum brakes are more susceptible to lockup, ABS mitigates the problem. Still, four-wheel disc brakes are optimal.

Airbags aplenty: A full set of airbags can improve an occupant's survivability dramatically. Frontal airbags are required on all cars; the side-impact variety are not. Side airbags that deploy from the seatbacks generally are intended to protect the occupant's torso, though some extend higher for head protection — especially in the absence of side curtain-type airbags.

The curtains deploy downward from the ceiling, covering all of the side windows. This type has proven critical in protecting car occupants, especially when T-boned by a higher vehicle. This type of crash poses a high risk of head injury, which is the least survivable type of trauma. (It's also the reason we have rejected NHTSA side-impact star ratings, as they do not factor head injury.)

There's little or no concern about side curtain-type airbags harming children. But conventional side-impact airbags can be dangerous, so they seldom appear in backseats. If you're concerned about a side-impact airbag in the front passenger seat, consider buying one of the Honda or Acura models that automatically disables the side bag when the seat occupant is leaning too close to the door.

The latest vehicles also feature advanced frontal airbags, which deploy at more than one level for occupants of different sizes. They employ the Occupant Classification System in the front passenger seat and crash-severity sensors to determine the correct airbag intensity. Advanced frontal airbags will be required in all cars and light trucks produced after Sept. 1, 2006. Until then, they are slowly being phased in.

Note that, even with OCS, airbags are not effective unless used with seat belts. It is a common misconception that seat belt use is unnecessary in the backseat. This is completely untrue. Aside from greater risk to the backseat occupants themselves, the Journal of the American Medical Association has reported that an unbelted rear-seat passenger increases the front-seat occupant's risk of death by 20 percent. Why? Because in a frontal collision at just 30 mph, an unbelted 120-pound backseat occupant will strike whatever's in front of him with the force of more than 1,000 pounds.

We can't emphasize enough the value of airbags. For just a few hundred dollars, they can be the difference between serious injury and walking away from a crash. If they seem expensive, how much is your health insurance deductible?

For $280, Volkswagen's Golf can be equipped with the manufacturer's Electronic Stabilization Program stability system.

Electronic stability system: Known by innumerable names, most of which include the word "stability," these computer-based systems brake individual wheels and control the throttle to keep the vehicle on the intended path in low-traction situations. Increasingly, this feature is standard on luxury vehicles, and Honda has committed to including it in every all-new and re-engineered vehicle within the next few years. Not many affordable cars offer the feature, but it does appear in models as inexpensive as Volkswagen's Golf.

Head restraints: Not simply "headrests" for occupant comfort, head restraints are intended to protect against whiplash injuries, particularly in a rear-end collision. Most of the vehicles tested by IIHS so far provide inadequate to fair protection, mainly because the head restraints don't extend high enough or aren't close enough to the occupant's head to prevent injury. Exceptions include the top two small cars listed above, which scored Good when equipped with certain seats. Among the other cars, the best score is Acceptable.

Buyers should look for head restraints — for every seating position — that extend high enough for the tallest likely occupant, and rest, or can be positioned, close to the head. Better still, active head restraints move forward in a collision to catch the occupant's head and ease it back. These remain rare in affordable cars; the 2006 Hyundai Sonata and some versions of the 2005 Subaru Impreza are exceptions.

Tilt/telescoping steering wheel: More modest vehicles have manually adjusted steering wheels that infrequently include a telescoping adjustment. This is unfortunate. Aside from making the driver as comfortable as possible, the telescoping adjustment in particular helps distance the driver properly from the airbag, regardless of his or her size. The next feature serves a similar purpose.

Adjustable pedals: Adjustable pedals serve a similar purpose as the telescoping steering wheel, allowing drivers to distance themselves optimally from the steering wheel without compromising pedal reach.

Headlights: Though they're mainly found in luxury vehicles, some more affordable cars offer xenon high-intensity-discharge headlights as an option. They are superior to conventional incandescent headlights because they are brighter, they cover a wider field of view, and they produce more ultraviolet light, which better illuminates reflective road signs. Even cars that lack this headlight type can vary in the amount of light they emit and how they distribute it. If you frequently drive in areas where wildlife strays onto the road, you might want to check a prospective vehicle's performance in this area before buying.

How About Hatchbacks and Wagons?

In cases where there are wagon or hatchback versions of a sedan model, frontal crash tests tend to yield similar results. This is helpful because wagons are usually low-volume vehicles, which the testing agencies don't crash. Possible differences in side-impact performance are less clear.

It's important to secure cargo items in wagons and hatchbacks to prevent them from turning into projectiles during a collision.

One of the greater and little-known hazards of hatchbacks and wagons involves cargo. Where a sedan carries cargo in a self-contained trunk, wagons and, to some extent, hatchbacks house people and cargo in the same cabin. In a collision, especially a frontal one, unrestrained cargo flies forward with a force exponentially greater than its weight. At 55 mph, a 20-pound parcel exceeds 1,000 pounds of force.

Whether the cargo stays in the back or not depends on many factors, such as the cargo's height relative to the seatbacks, how much the vehicle's rear end rises upon impact and innumerable other dynamics.

The only safe way to travel with cargo in a hatchback or wagon (or an SUV for that matter) is to restrain it. Tying it down is the most obvious cure, but some wagons offer retractable nets or cages at the backseat's backrests that can help contain objects in the cargo area. Is this step a drag? Yes. The most careful drivers will do it anyway. If you chose not to, understand at least that you're playing the odds.

Children and Cars

Overall, cars have pros and cons as child carriers. Their height facilitates child seat installation compared to many SUVs. At the same time, backseat space seems more limited than ever. Children might be small, but child-safety seats are huge, and it's now recommended that children stay in booster seats until much later in life. Few cars will accommodate two child seats and an adult in the backseat.

Compared to minivans and some SUVs, cars can hinder child-seat installation. Low ceilings and contoured backseats, especially in coupes, can prevent a secure fit. Securing the seat with seat belts, the conventional method, calls for the adult to put a knee into the seat while tightening the belt — hard to do in the back of a 2+2. People in this situation should consider a child seat with LATCH straps for simpler installation. All new cars have at least two LATCH anchors in their backseat.

The rules for transporting children in cars are the same as they are for other vehicle types: The proper child-safety or booster seat should be used for their age and size, and they should be secured in the backseat. The best possible place for the child is belted into the center position. This keeps the child as far away as possible from the car's perimeter on all sides.

The front passenger seat should be avoided at all costs, especially with a rearward-facing child-safety seat. If you must place a child seat in the front, in a two-seat car, you must have either OCS or a defeat switch to turn off the airbag.