> In 2013, 50,000 people suffered fatal brain injuries; 19 percent of those were due to car crashes. Among persons aged 5 to 24, motor vehicle crashes were the leading cause of death from fatal TBI (Traumatic brain injury). It’s likely that a good proportion of the 9,500 people might have been saved had they been wearing a helmet in the car.

https://www.treehugger.com/cars/why-all-cars-should-be-hi-vi...

https://www.cdc.gov/traumaticbraininjury/get_the_facts.html

The data disagree with you.