The $17.35 million fine is the largest penalty allowed under the law, the U.S. Department of Transportation said Tuesday.
The federal government requires automakers notify the National Highway Traffic Safety Administration within five days if the company discovers a safety defect. Toyota has already paid three separate fines totaling $48.8 million for failing to report safety problems in a timely manner.
But this fine, the fourth in two and a half years, is the biggest one-time fine. NHTSA said Toyota knew of 63 cases where floormats were causing interference with the accelerator pedal in model year 2010 Lexus RX 350s. Toyota started learning of those cases in 2009, and didn't report them to NHTSA until the agency's Office of Defect Investigations began noticing a trend in complaints logged into its system.
"It's critical to the safety of the driving public that manufacturers report safety defects in a timely manner," said NHTSA Administrator David Strickland. "Every moment of delay has the potential to lead to deaths or injuries on our nation's highways."
In June, Toyota recalled 154,000 model year 2010 Lexus RX350 and Lexus RX450h vehicles to address the problem.
Faulty floormats are what caused California Highway Patrol Office Mark Saylor to lose control of the Lexus he was driving in southern California in August 2008. The police officer, his wife, his daughter and his brother in law all died in a fiery crash after the brother-in-law called 911 saying they could not stop the car from accelerating. The harrowing crash launched Toyota's sudden acceleration issues into the forefront, and NHTSA investigations revealed the company was aware of problems but dragging its feet instead of conducting a recall.
NHTSA said that as part of the settlement, Toyota has agreed to make internal changes to their review of safety-related issues in the United States.
Toyota said it agreed to the fine to "avoid a time-consuming dispute."
"Toyota is dedicated to the safety of our customers, and we continue to strengthen our data collection and evaluation process to ensure we are prepared to take swift action to meet customers' needs," said Ray Tanguay, chief quality officer of Toyota North America, in a statement.
Toyota's sudden acceleration problems will likely be back in the headlines in 2013, when the first of several trials addressing the issue will start playing out in court. The family of 66-year-old Paul Van Alfen, a Utah man who died when he sped off an exit ramp and into a wall, brought the case to court in the federal courts. His son's fiance, Charlene Lloyd, also died that day.
The trial is expected to start in February in the U.S. District Court of Central California.