American motorcycle manufacturer Harley-Davidson has agreed to pay a civil fine of $US12 million ($A15.6 million) after it settled a dispute in which the sale of its Screamin' Eagle Race Tuners and Screamin' Eagle Pro Super Tuners was alleged to contravene Environmental Protection Agency emissions standards in the US.
Harley-Davidson will also have to contribute a further $US3 million ($A3.9 million) to an unrelated 'clean air project'.
The US Government alleged that Harley-Davidson had sold around 340,000 Super Tuners since 2008, with the performance modification then permitting Harley-Davidson motorcycles to produce more pollutants than the manufacturer had previously certified to the EPA.
Screamin' Eagle Super Tuners alter a Harley-Davidson's ignition and fuel mapping, allowing tuners to alter power and torque curves and unlock greater levels of performance.
The unit is a common performance upgrade for Harley-Davidson owners, regularly going hand in hand with aftermarket or non-standard air cleaners and exhaust systems.
The modification boosts a motorcycle's engine output but also raises its emissions of hydrocarbons and nitrogen oxides, says the EPA.
Harley-Davidson has refused to admit liability in the case, stating the Super Tuners were only sold for 'competition use'.
As part of the settlement, Harley-Davidson will stop selling the Super Tuners in the US from this month (August), and will buy back and then destroy any remaining dealership stock of the devices.
"We disagree with the EPA's position but we're going to move forward and settle [the case]," said a Harley-Davidson spokesperson.
According to Cynthia Giles, assistant administrator for the EPA's Office of Enforcement and Compliance Assurance, the case was a major win for emissions control.
"This settlement immediately stops the sale of illegal aftermarket defeat devices used on public roads that threaten the air we breathe," she said.
"Harley-Davidson is taking important steps to buy back the 'super tuners' from their dealers and destroy them, while funding projects to mitigate the pollution they caused."
Click here to read the EPA summary of the settlement.
It is not yet known how the case will affect the sale and supply of Screamin' Eagle Super Turners in other world markets; Bikesales.com.au will bring you more information as it comes to hand.