Tens of thousands of Turnpike motorists have been socked with falsely inflated Fast Lane bills because the company that provided their transponders violated its multimillion-dollar contract by failing to inspect the system, a state audit has found.

State Auditor Joseph DeNucci -who investigated the overcharges after a front-page Herald expose in February - found that Fast Lane provider TransCore failed to inspect transponder equipment over the past two years as mandated in its $11 million-a-year contract.