No matter how your car performs on the road or what its other capabilities are, its ultimate job comes down to safety: How does it protect you and your family in the event of an accident?
“How safe your car is in a crash could save your life,” says Clarence Ditlow, executive director of the Center for Auto Safety and one of the longest-tenured auto safety experts in the country.
“Crash tests – and now crash avoidance evaluations – go beyond what’s required by regulation and demonstrate that not all vehicles perform the same in protecting people when crashes happen or in helping them to avoid crashes in the first place,” says Russ Rader, communications director for the Insurance Institute for Highway Safety (IIHS).
Two organizations publish ratings of cars’ performance in a series of similar but mostly complementary crash tests: IIHS, a private trade group representing the insurance industry, and the National Highway Traffic Safety Administration (NHTSA), a branch of the federal Department of Transportation.
- NHTSA rates cars on a five-star scale in four tests: a front crash, a side crash from another car, a side crash into a pole (simulating spinning off the road and hitting a tree or a phone pole), and a rating for a vehicle’s propensity to roll over. It also provides an overall five-star rating that aggregates the other ratings.
- The IIHS rates cars in four different crash tests: two offset front crash tests that represent the majority of head-on collisions, where vehicles only clip part of each other’s front ends (each test represents a different portion of the width of the car), a side crash simulating being hit by an SUV, and a roof-strength test showing how a car holds up in a rollover. Its ratings represent a car’s level of protection from injury risk in each test: Good, Acceptable, Marginal, and Poor. It includes an overall rating that encompasses these crash-test scores as well as ratings in the Institute’s tests of accident avoidance technologies, effective head-restraint design (for rear-end crashes), headlight performance, and ease of child-seat installation in its Top Safety Pick and Top Safety Pick + ratings. (You can find them if you look on its site by category.)
The tests and their corresponding ratings started as a way to address the types of crashes that most often led to severe injuries. Automakers want to advertise good ratings, as they redesign each model they incorporate features that guarantee good ratings on the tests. As the majority of cars from each new generation begin to score well on the existing tests, the IIHS and NHTSA come up with new tests to address a wider range of accidents. So the more tests a car does well on, the wider variety of accidents it could help you survive. The safest cars are those that get top scores across the board.
Neither agency rates every car, however. Luxury cars are hardly tested at all. While it’s impossible to know how a vehicle that’s not tested would perform, it’s a safe bet that automakers will focus their safety resources on the most popular cars and SUVs that they expect the agencies to test. Older models are likely to provide less comprehensive crash protection, even if they’re still on the market. That’s because it’s very difficult and expensive to retrofit older designs with modern crash structures once they’re already rolling off the assembly line. So any similarly sized new car you buy will likely be far safer than what you’re driving now. If you’re shopping for an older car, it’s important to buy the most recent model you can afford.
In 2009, IIHS demonstrated how far crash safety has advanced when it crashed a then-new Chevrolet Malibu head on into a 1959 Chevrolet Bel Air, built ten years before any safety standards or ratings were developed. The Bel Air’s crash-test dummy sustained severe damage; the dummy in the much smaller Malibu fared fine.
To protect occupants in a crash, a car has to have two major attributes: Effective restraint systems that hold an occupant in place and cushion them from contacting any hard parts of their car’s interior (or of the vehicle crashing into them), and a strong passenger compartment to maintain space around the occupant where they can survive in a crash. The best restraint systems, like seat belts, do no good if the dashboard or the roof caves in on you where you sit. Likewise, the best safety structure does no good if you get catapulted through the windshield because the belts don’t hold you in.
Today many cars get the top “Good” crash test ratings across the board from IIHS, and five-star overall ratings from NHTSA (with four stars in some individual categories.) That means they provide good protection in a wide variety of accidents. The newest tests that still set some cars apart are IIHS’s new 25 percent small overlap front test, and NHTSA’s side pole test, so those are the ones to pay closest attention to if you’re shopping for a new car – especially if you have an inexperienced driver in your household.
Beyond the Crash Tests
Crash test performance isn’t everything. Basic laws of physics dictate that larger, heavier cars hold up better in accidents than lighter, lower ones do. A strong crash structure that maintains the space inside the passenger compartment is more important in smaller cars. “Bigger, heavier vehicles are more protective in crashes than smaller, lighter ones,” says Rader. “A small car with good safety ratings doesn’t mean that it’s just as safe as a bigger, heavier one with the same ratings.” With that, it’s tempting to think that everyone should just go out and buy the biggest, tallest, and heaviest new car they can afford, but that doesn’t help if you run off the road and roll over or hit a tree. (Plus, we don’t all want to be driving semi-trucks.)
Of course, the best way to survive an accident is not to get into one in the first place. Pre-collision warning, automatic braking, lane departure warning, and lane keeping assistance systems reduce the number and severity of accidents drivers get into. So IIHS has recently incorporated ratings for these systems into its overarching Top Safety Pick and Top Safety Pick+s ratings. Besides small-overlap test performance and NHTSA’s side pole test, these are the systems that distinguish the safest cars today.
Modern technologies aimed at reducing injuries in accidents such as crumple zones, safety structures, air bags, and active driving aids have made cars much more likely to incur damage in even minor accidents, and much more expensive to repair afterward. They’re still better at doing their ultimate job of protecting you and your family inside when something goes wrong though.