At the PRI show last month they put on a showing of the documentary "Yellow, Yellow, Yellow" about the Holmatro Safety Team; in it there was a segment on Scott Dixon, who had concussion symptoms after the race at Baltimore a few years ago even though he wasn't in an accident. They reviewed the in-car video and discovered that during a restart, while accelerating from very low speeds on the bumpy street surface, his head was ping-ponging rapidly between his head restraints. From that discovery they developed a 2-stage, progressive padding to mitigate the effect. It's all about continuous improvement.