First of all, the floor mat in question didn't belong to the ES350 (actually, the ES350 didn't belong to Officer Saylor -- it was a dealer loaner while his car was being worked on). The mats in the ES350 that crashed were from a RX400h. Not only that, they were those thick, all-weather hard rubber mats. Regardless, because the dealer had placed the wrong mats into the wrong car, there was no way to properly mount them. Also, it seems that the pedal design of the ES350 also played a role. The NHTSA discovered that, "Beyond the main pivot, the lever is not hinged and has no means for relieving forces caused by interferences." We think that means it can easily get stuck.
But that's not all. The NHTSA had also learned from a previous ES350 investigation that, "the Lexus ES braking system loses power-assist when the throttle is fully opened, increasing braking distance fivefold." That's not good. And the brakes had signs of heavy wear and damage, "Rotors were discolored and heated, had very rough surfaces, had substantial deposits of brake pad material, and showed signs of bright orange oxidation on the cooling fins consistent with endured braking."
Additionally, because the Lexus has push button start, the operator must push the button for three seconds before the engine will shut off. A piece of info obviously and sadly not known by Officer Saylor. The San Diego County Sheriff's office is leading the investigation and has not yet released their final report. We'll keep you posted on that, but as they say in plane crashes, looks like the holes in the swiss cheese all lined up.
[Source: LA Times]