Here's How IIHS Crash Tests Have Evolved Over Almost 30 Years

The IIHS’ first crash test scenario was the moderate overlap crash test, where 40 percent of a vehicle’s width strikes a deformable barrier on the driver’s side at 40 mph. This test was implemented in 1995, when research showed that offset crashes are at least as common as full-frontal crashes, and offset crashes caused significant lower-limb injuries. When the IIHS first began testing cars in moderate overlap crash scenarios, most cars scored poorly, but now most cars pass this test with flying colors, so much so that the IIHS decided to update the moderate overlap crash test recently with a child-sized dummy in the rear seat

Since whiplash and neck sprain injuries were the most frequently reported injuries in U.S. auto insurance claims, the IIHS first began analyzing head restraint geometry in 1995 to mitigate this common claim. In 2004, the Institute began a dynamic test to simulate getting rear-ended with a special crash test dummy with a simulated spine to encourage better head restraint designs. These test measures worked so well that the Institute decided to end this simulated rear impact test in 2022 because almost every new car it tested received its highest rating of good. In 1995, a mere 3 percent of measured head restraints received good geometric ratings and 82 percent were given the IIHS’ lowest rating, poor. A government standard went into effect in September 2010 that guaranteed nearly all new head restraints would earn a rating of good. The Institute is exploring how it may update the test in the future to encourage further improvements.

The IIHS began its original side impact crash test program in 2003 since side crashes account for about a quarter of vehicle occupant deaths in the U.S., and the Institute noticed that the government’s side impact crash tests didn’t embody real-world crash scenarios. The federal side impact crash test uses a barrier that sits at the height of a standard car’s hood, but most of the vehicles on modern roads are trucks and SUVs. In the original side impact IIHS crash test, a 3,300-pound barrier with the approximate height of an SUV hit the driver’s side of the test vehicle at 31 mph with a driver dummy that represents the size of a 5th percentile woman, and the same small sized dummy in the driver’s side rear seat. Smaller dummies are used because women are more likely to suffer serious head injuries in real-world side impacts than men. In early testing, only about 20 percent of vehicles tested earned good ratings, and nearly all others were rated poor. The IIHS recently updated its side impact crash test to account for the increasing size and weight of modern cars, which will be touched on later in the slideshow.

The IIHS began testing bumper designs in about 2006 to promote bumper designs that actually bump and prevent damage in low-speed impacts. These tests typically focused on a particular size class of car to allow new car shoppers a thorough understanding of each class and how different vehicles’ bumpers performed. Though consumers were outraged by the sometimes shockingly expensive repair bills that would arise from these very slow impacts, this outrage didn’t necessarily translate directly to consumer buying habits in the same way that the IIHS’ higher speed crash testing did. Since manufacturers didn’t see much shift in buyer behavior, not much was done to improve performance in these low-speed tests, and SUVs and pickup trucks remain exempt from any bumper performance standards. The Institute decided to shift its efforts to other important crash tests that were being developed at the time like the rear-impact sled test and the small overlap crash test.

The roof strength test was implemented by the IIHS in 2009, and did just what the name suggests; evaluated the strength of a vehicle’s roof to gauge the likelihood of occupant safety and survival. A good rating in the roof strength test was issued to vehicles that could withstand the force of at least 4 times the vehicle’s weight before the roof crushed five inches. Every roof strength test would subject the test vehicle to a pneumatic angled metal plate that would slowly and constantly increase the force on the roof until it crushed five inches. The Institute concluded roof strength testing in 2022 because nearly all vehicles were earning good ratings, and an updated federal standard which was similar to the IIHS’ roof strength testing was implemented between 2013 and 2017 and established criteria similar to the Institute’s requirements for a good rating. Deaths due to rollovers have declined dramatically in recent decades, partially due to the popularity of electronic stability control and the increased standards set by the IIHS.

The IIHS has sporadically performed car-to-car crash tests to illustrate various considerations that buyers should take into account before buying a car. In the example crash test shown on this slide, the Institute pitted small cars against the same manufacturer’s larger cars to illustrate how vehicle size and weight affect crash performance. Despite impressive advancements in the safety of small cars over the years, the laws of physics still apply. In real-world car-to-car crashes, larger vehicles fare better than smaller ones, so the IIHS performed these crash tests to illustrate that even a good-rated small car doesn’t offer the same occupant protection in the event of a crash with a larger vehicle. An IIHS spokesperson told me that this is particularly important knowledge for parents who are car shopping for a teen driver; not that all teens should be driving tanks, but that even a used midsize car can provide more safety than a brand new small car.

The IIHS introduced this test in 2012 to replicate what happens when a small portion of a car collides with another vehicle or an object like a tree or utility pole. Small overlap frontal crashes subject the typically un-integral outer edges of a vehicle to significant crash forces, though the main crush-zone structures of most modern cars is concentrated in the middle 50 percent of a car’s front end. In small overlap crashes, crash forces bypass most crush zone structures and go directly into the front wheel, suspension system and firewall. This tougher test requires vehicle safety cages to resist crash forces that would normally be alleviated by front crush zones in a more direct crash.

The first IIHS tests of automated front crash prevention systems was implemented in 2013, and tested vehicle detection of vehicle-to-vehicle, and front-to-rear crashes. In the early days of this test, ratings were assigned based on tests conducted at 12 and 25 miles per hour, as a technician drove the vehicle straight toward a stationary dummy car target that simulated the back of a real car. The benefits of an effective front crash prevention system are obvious, even if these systems don’t entirely avoid an impact, they are likely to significantly reduce the speed at which the impact occurs, thus increasing survival chances and minimizing injury potential for all parties involved. The IIHS stopped its vehicle-to-vehicle evaluation of front crash prevention systems in 2022 because virtually all new vehicles were earning advanced or superior ratings, partially due to a voluntary commitment by automakers that the IIHS helped broker. The Institute is in the process of developing a more challenging test to account for higher speed tests and crashes that involve non-passenger vehicles, as well.

The IIHS established its Lower Anchors and Tethers for Children (LATCH) rating program in 2015 to encourage manufacturers to design LATCH hardware that is easier to use, since parents are more likely to install a child restraint system correctly when proper installation is a simple task. LATCH ratings were implemented in 2015, and include several criteria including the accessibility of lower seat anchors, the force necessary to attach the child seat, clearance angle that the vehicle provides to allow easy installation, physical anchor location, and the presence of confusing hardware that could potentially be misconstrued as the tether anchor. LATCH ratings indicate how easy each vehicle makes it to achieve a correct and tight installation of a child restraint when using the dedicated hardware. LATCH ratings don’t indicate vehicle safety, simply the ease with which a vehicle facilitates proper child restraint installation.

About half of all fatal U.S. crashes happen in the dark, and more than a quarter happen on unlit roads, proving the importance of good headlights in preventing crashes in the dark. Government headlight regulations don’t guarantee consistency in headlight performance, so the IIHS began evaluating headlight performance in an array of criteria to determine their effectiveness. I won’t get into the specifics of how headlights are measured since it is quite technical, but if you’d like to know more check out the IIHS website here. Headlights are measured on the right edge of the roadway, the left edge of the travel lane, distance on a straightaway, and glare to other road users. High and low beams are measured, with more weight placed on low beams because they are most frequently used. According to IIHS data, vehicles with good-rated headlights have 19 percent fewer night time single-vehicle crashes than vehicles with poor-rated headlights.

The IIHS introduced the passenger side small overlap test in 2017 when its internal research tests showed that some manufacturers were only reinforcing their vehicles’ driver-side crash structures to perform well in the driver’s side small overlap test without adding protection for passengers. The passenger side small overlap test is the same as the driver’s side test, but the vehicle has dummies in the driver and passenger seat. Early tests showed discrepancies between driver’s side small overlap crash test performance and passenger side performance, but most new vehicles earn good ratings in both categories.

The IIHS began testing semi-truck trailer underride guards in 2016 since crashes where vehicles underride semi-truck trailers are often deadly since the smaller vehicle travels under the trailer and the point of impact is often directly to the occupant compartment. The Industry tests underride guards at three overlap intervals, head-on or full-width where the car crashes directly into the trailer, 50 percent overlap where half of the car’s width overlaps with the rear of the trailer, and 30 percent overlap with just 30 percent of the car’s width overlapping with the trailer. All tests are conducted at 35 miles per hour. Early tests revealed significant flaws in underride guards particularly in partial overlap impacts, but now that most new trailers provide adequate safety, the Institute has stopped testing underride guards though it is planning an updated test.

Since some front crash-prevention systems don’t detect or don’t accurately detect pedestrians and internal research revealed a benefit for systems that recognize pedestrians, the IIHS began testing for pedestrian detection in 2019. There are two pedestrian detection scenarios that the IIHS tests for at both 12 and 25 mph; perpendicular adults crossing an unobstructed roadway in both daytime and night time scenarios, and a child darting out from behind a parked car conducted in the daytime only. There’s also a test simulating an adult near the right edge of the road traveling in the same direction of traffic, and this test is run at 25 and 37 mph in both day and night scenarios. Again, the benefits of vehicles accurately detecting pedestrians on a roadway are clearly apparent, but the IIHS scoring is less black and white; check out the website to learn the specifics of these rankings.

The original IIHS side crash test involved a 3,300-pound barrier impacting a stationary car at 31 mph, but the updated side crash test involves a 4,200-pound barrier that strikes the side of a stationary car at 37 mph. This test was updated to more accurately reflect the modern automotive landscape, which is littered with bigger, heavier trucks and SUVs as well as electric vehicles. The updated test subjects test vehicles to 82 percent more energy than the original test. There are still two small female sized dummies in each test vehicle, one in the driver’s seat and one directly behind the driver in the back seat.

The IIHS updated the moderate overlap crash test in 2022 to include a small female dummy sitting as a rear passenger to address lagging occupant protection for rear occupants. This updated test has revealed that many vehicles that provide good protection for front seat occupants in the event of a moderate overlap crash don’t provide good protection for rear seat occupants. Most of the issues that arise with rear-seat occupants include poor management of dummy movement during the crash and lap belts that can slide up onto the abdomen of the dummy which significantly increases the likelihood of organ damage to rear seat occupants.