After the Tesla Model S failed to achieve the top crash rating from IIHS last year, the company claimed to have made ‘production change’ to improve results on the small overlap test, which was the only issue to obtain the top rating.

The Insurance Institute for Highway Safety (IIHS) tested the vehicle again with the modifications, but they say that it had the same results and therefore, the rating didn’t change.

In the original test, IIHS said that the safety belt of the Model S “allowed the dummy’s torso to move too far forward.”

Today, they issued a press release stating that the obtained the same results in the second test:

“Tesla made changes to the safety belt in vehicles built after January with the intent of reducing the dummy’s forward movement. However, when IIHS tested the modified Model S, the same problem occurred, and the rating didn’t change.”

Tesla responded in a statement (via CNBC) suggesting that the test was designed to suit the IIHS’s “own subjective purposes”:

“Tesla’s Model S received the highest rating in IIHS’s crash testing in every category except for one, the small overlap front crash test, where it received the second highest rating available. While IIHS and dozens of other private industry groups around the world have methods and motivations that suit their own subjective purposes, the most objective and accurate independent testing of vehicle safety is currently done by the U.S. government, which found Model S and Model X to be the two cars with the lowest probability of injury of any cars that it has ever tested, making them the safest cars in history.”

The Model S did indeed receive the highest safety rating from NHTSA, which doesn’t perform the small overlap crash test.

Here’s the new overlap test performed by the IIHS:

Furthermore, the institute ended up lowering the Model S’ structural integrity results from the test after seeing a greater intrusion on the second test:

“Although the two tested vehicles had identical structure, the second test resulted in greater intrusion into the driver’s space because the left front wheel movement wasn’t consistent. Maximum intrusion increased from less than 2 inches to 11 inches in the lower part and to 5 inches at the instrument panel in the second test. The first test resulted in a good rating for structural integrity, while the second test resulted in an acceptable structural rating. The two tests’ structural ratings were combined, resulting in acceptable structure and an acceptable rating overall for the Model S.The greater deformation in the second test also resulted in damage to the left front corner of the battery case. The deformation was limited to an area that didn’t contain battery cells in the tested vehicle, so this damage didn’t affect the rating. Higher-performance variants of the Model S could have battery cells in this area, but, according to Tesla, they also have different structure. They haven’t been tested separately and aren’t covered by this rating.

The IIHS tested the Model S with a 75 kWh battery pack. The “higher-performance variants of the Model S” that they are referring to is the Model S P100D, which has a 100 kWh battery pack and Tesla had to change its structure to fit that much energy capacity in the same pack size.

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