Congressional Democrats sharply questioned Thursday efforts by Toyota Motor Corp. to investigate vehicle electronics to see whether they are linked to unintended acceleration.


Henry Waxman, chairman of the House of Representatives Energy and Commerce Committee, led an aggressive critique of Toyota and its engineering consultant, Exponent Inc., at a hearing centered on Toyota’s professed belief that its software-driven throttle systems are sound.


Waxman and other lawmakers said Exponent has not produced sufficient documents to support Toyota’s contention, and that submitted material does not fully answer basic questions.