Lawsuit Alleges GM Cheated On Diesel Pickup Truck Emissions

DETROIT (CBSDetroit/AP) - Shares of General Motors are down more than 2 percent Thursday after a lawsuit alleged that its diesel pickup trucks cheat on emissions tests.

The lawsuit filed in Detroit federal court says that 705,000 pickups with Duramax diesel engines have three devices on them that are rigged to allow more pollution on the road than during government lab tests.

GM said the allegations are without merit saying their trucks meet government standards and they will "vigorously defend" themselves.

The lawsuit filed by the Hagens Berman firm of Seattle alleges the trucks emit two to five times the legal limit for harmful nitrogen oxide. Also named as a defendant is Robert Bosch LLC, which made GM's electronic diesel controls. A message was left for a Bosch spokeswoman.

The law firm involved is encouraging owners to join in the lawsuit.

Diesel engines have been under scrutiny worldwide after Volkswagen admitted that its diesel cars cheated on tests -- but unlike VW and Fiat Chrysler emission testing issues this does not involve the US government.

(© Copyright 2017 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)