Despite the reputation of 1970s land yachts, today’s vehicles are built better than ever in an attempt to meet strict crash test standards. Just watch any video of new car vs classic car crash tests on YouTube for a cringe-worthy way to pass the time to see the difference safety features make. Today, we have compact cars with 10 airbags, active safety systems, and five-star safety ratings. Here’s how we got here, and what those safety ratings mean.

History of Safety Ratings

Safety rating scores in the United States typically come from one of two acronyms, the NHTSA or IIHS. The National Highway Traffic Safety Administration (NHTSA) is part of the federal Department of Transportation, tasked with the mission of saving lives, preventing injuries, and reducing vehicle crashes. The IIHS is the Insurance Institute for Highway Safety, a nonprofit organization funded by the insurance companies, with a similar goal. Since 1959, the IIHS has aimed to reduce the number of vehicle crashes, deaths and injuries, and the amount of property damage resulting from auto accidents (less crashes, more profit in insurance). While searching vehicles sold worldwide, like the Ford Focus, you might see an NCAP rating. Those are from the European New Car Assessment Programme, which is basically the EU version of the above organizations.

No matter the source, the goal of publicized safety ratings is to provide information to vehicle buyers. In theory this makes smarter shoppers, which produces safer buying habits, thus lowering the injury and fatality rate of vehicle accidents. Generally, it’s worked. Even though the number of cars on the road has massively increased since the 1970s, traffic injuries and fatalities reduced from 1972 high of over 52,000 per year through 2012, with just over 32,000. Even though active safety tech is a hot trend, five-star safety ratings won’t be going out of style.

Safety Scores Deconstructed

The different levels of stars in a crash test rating do have a meaning, and more than just “more is better.” After each impact test, the NHTSA reviews the footage to determine the likelihood of a serious injury. Specifically, a serious injury means an ambulance ride to a hospital, not a sprain or bruises.

The possible scores mean:

  • 5 Stars (10% or less chance of serious injury)
  • 4 Stars (11-20% chance of serious injury)
  • 3 Stars (21-35% chance of serious injury)
  • 2 Stars (36-45% chance of serious injury)
  • 1 Star (46% or greater chance of serious injury)

And to answer your question: yes, a vehicle can get zero stars. Have a look at the Renault Kwid, demonstrating what a zero-star rating looks like. Thankfully, this model is not sold in North America.

The IIHS also tests and rates the safety of vehicles, but uses slightly different criteria than the NHTSA, testing crashworthiness and crash avoidance. The former is how well a vehicle protects its occupants in an impact, and the latter looks at tech that can prevent a crash. Instead of stars, the IIHS uses terms like “Good” (highest) through “Poor” (lowest) to get the point across to readers. The IIHS tests different areas too, like headlights and headrests, so you should be checking both sources for the most accurate picture of a vehicle’s safety.

Testing

Front impact

When you see a commercial with a car in a lab getting destroyed against a wall in slow motion, that’s the NHTSA’s front impact test. The point is to evaluate how the test dummies “survive” a head on collision with another vehicle, or when impacting a solid object, like driving into a wall. By measuring the impact forces, what parts of the dummy gets hit by objects, and multiple other criteria, the NHTSA can determine if the occupants would walk away, ride away in an ambulance, or not survive the wreck. Five stars here means little cabin intrusion in an accident, and low risk of serious injury. Here is what a five-star crash rating looks like in the Tesla Model X. Notice how the passenger compartment, and even the windows all stayed in place, while the front crumple zone absorbed the crash energy. That is how it should work. A one-star rating means serious cabin intrusion and the potential for fatalities. This is a one-star crash. Notice that the passenger cabin acts like a part of the crumple zone, pummeling and mangling that dummy inside.

Moderate overlap

This IIHS test also evaluates head-on collisions, but tries to simulate real world conditions. Impacts won’t always be head on, so this test simulates accidents that happen while turning, or impacting a wall at an angle. Forty percent of the front of the vehicle impacts a test wall, increasing the collision force on a smaller area of the vehicle. To earn a “Good” score from the IIHS, the dummy’s crash data would indicate a low risk of any significant injuries, with hard parts like heads and knees only impacting airbags. For a “Good” moderate overlap score, and a Top Safety Pick+ recommendation, look at the Hyundai Elantra.

Side impact

When a driver runs a red light or stop sign, your vehicle could get T-boned. Without an engine or crumple zone to protect the passengers, side-impact collisions were incredibly damaging to the vehicle and its occupants 50 years ago. In the 1980s, anti-intrusion beams in the doors created a kind of cage for the cabin. Then Volvo mounted side-impact airbags on the seats of its 1995 850 wagon. These met the new mandate that passengers survive a 30 mph side impact. Around 2005, you might have noticed windows getting smaller as the “beltline” of the vehicle rose (think modern Chevy Camaro). This is an attempt to design-in safety by reducing glass and increasing the protective body structure. This design is especially important in side-impact tests, and it’s no coincidence the Camaro has a five-star side impact score.

Small offset

This nasty IIHS test made a mockery out of the safest vehicles on the road at its debut in 2012. To further simulate real world accidents, the IIHS shows us what happens when you clip another vehicle, striking only 25% of your vehicle on the stationary object. When the entire front end absorbs the impact, it’s a large area to absorb crash energy. Reduce that size by 75%, and the vehicles disintegrated, with the front wheel smashing through the cabin and resting where the front passenger was formerly living. Fear not, manufacturers have adapted to this test, and are again earning high marks. Look to vehicles like the Kia Sorento, Lincoln Continental, and Subaru Impreza, which all earn the highest scores by remaining solid and intact after the small offset test.

Rollover/Roof Strength

You can probably guess this test from the name. Emergency maneuvers created unpredictable handling and unflattering news coverage for the Ford Explorer back in 2000 (that SUV is unrelated to the current crossover Explorer). With roof strength on their mind, the NHTSA set out to test how occupants survive a rollover. Rather than slamming into a test wall at high speed, the roof test slowly applies pressure to the vehicle roof, and measures the force needed to crush it five inches. Vehicles with a “Good” score, like the BMW X3, score well here by taking over 18,000 pounds to crush the roof. That’s an impressive four-and-a-half times the vehicle’s weight. The X3 is well built overall, earning the highest “Good” score in every category, a superior crash prevention rating, and a Top Safety Pick+ award. For a real test, they should probably replace the wall in crash tests with another BMW X3.