Preliminary federal investigation into a highly publicized unintended-acceleration crash involving a Lexus ES 350 crash this past August is pointing toward incorrect floor mats as a significant factor. The cause of the crash is described as “very excessive speed” linked to the accelerator being fully depressed. (Read "More than floor mats: NHTSA report gives more details on Lexus crash.")
 
Toyota issued a recall on 3.8 million cars to have owners remove the floor mats from the vehicles. But the other part of the equation in the investigation is the accelerator pedal itself. An initial investigation of the crashed car found the rubberized plastic all-weather floor mat was fused to the rubberized plastic accelerator pedal in the fire that followed the crash (pdf). That mat wasn’t intended for the ES; rather it was a mat from an RX 400h.
 
The report also noted that the Lexus’s accelerator “is not hinged and has no means for relieving forces caused by interferences.” All gas pedals move up and down to control the engine speed, and most are hinged either at the top or the bottom. Some pedals also tilt relative to the arm they’re mounted on (though this has no effect on the throttle. The National Highway Traffic Safety Administration (NHTSA) seems to imply that if the pedal had a second hinge, it might have been easier for the driver to get it unstuck from the floor mat.
 
We checked our Auto Test Center parking lot to find how many cars had such a double-hinged pedal. Of 45 cars we checked, we found only the Kia Optima LX four-cylinder had a double-hinged pedal (show right)—our Optima EX V6 did not. In the LX sedan, the pedal was so high off the floor that it seems unlikely that an unsecured floor mat could reach it, as investigators suggest may have been the case in the Lexus crash. All other pedals checked in our lot were rigid, one-piece designs (see above), some hinged at the top, and some at the bottom.
 
We’re not sure whether the double-hinged design would help or not. But it seems an answer not many automakers are pursuing. For its part, Toyota says it is working on solutions that prevent the throttle from sticking, rather than those that would mitigate the effects of a stuck throttle.

 —Eric Evarts

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