A contingent of small firms with expertise in class actions and products liability litigation are behind a legal onslaught against Toyota Motor Sales USA Inc. following reports of sudden acceleration in many of its most popular vehicle models.

As of Friday, Toyota had attracted more than a dozen class actions filed on behalf of consumers who allege that Toyota’s failure to adequately disclose problems with its accelerator pedals amounted to fraud. At least three other suits were filed on behalf of people injured, or whose family members were killed, when their Toyota accelerated without warning. Additional firms planned shareholder suits against Toyota, whose stock value has dropped beneath the weight of the negative publicity.