* Robert Bosch to pay $327.5 million to compensate U.S. owners
* VW costs could hit $4 billion if regulators don't approve fixes
* U.S. 3.0 liter owners to get $7,000-$16,000 compensation for fix (Adds Bosch statement, Audi comment)
By David Shepardson
WASHINGTON, Feb 1 (Reuters) - Volkswagen AG has agreed to pay at least $1.22 billion to fix or buy back nearly 80,000 polluting U.S. 3.0 liter diesel-engine vehicles to settle claims it fitted illegal emissions-cheating software to the cars, court documents showed.
German auto supplier Robert Bosch GmbH also agreed to pay $327.5 million to U.S. diesel VW owners, according to the documents filed late Tuesday.
Volkswagen could be forced to pay up to $4.04 billion if regulators don't approve fixes for all vehicles. In December, VW said it had agreed to buy back 20,000 vehicles and expected to win approval to fix another 60,000.
The settlement is the last major hurdle to Volkswagen moving beyond the scandal over its installation of secret software in hundreds of thousands of U.S. diesel cars to cheat exhaust emissions tests, although it still faces suits from some U.S. states and investors.
Volkswagen has already announced 18.2 billion euros ($19.63 billion) of provisions to cover the costs of "Dieselgate" and a source familiar with the matter said last month that its total bill was likely to remain below 20 billion euros.
Volkswagen's luxury car unit Audi said on Wednesday it was reviewing whether it needed to put aside more provisions to cover the costs of a U.S. settlement of the scandal, on top of the 980 million euros it already set aside.
"We are using the court documents to review what we still need to set aside for the annual accounts," an Audi spokesman said in Germany.
Under the VW settlement that must be approved by a U.S. judge, owners of 3.0 liter vehicles who opt for fixes will get compensation of between $7,000 and $16,000 from Volkswagen if emissions fixes are approved in a timely fashion -- and the automaker will pay another $500 if the fix affects a vehicle's performance.
Owners who opt for a buyback will get $7,500 on top of the value of the vehicle.
The U.S. Federal Trade Commission, which had sued VW, voted unanimously to back the deal.
Volkswagen Group of America chief executive Hinrich Woebcken said, with the agreement, all owners of polluting diesels "will have a resolution available to them. We will continue to work to earn back the trust of all our stakeholders."
VW has been barred from selling diesel vehicles in the United States since late 2015.
VW has agreed to repurchase the 2009-2012 Volkswagen and Audi 3.0 liter vehicles, but believes it will be able to fix the 2013-2016 Volkswagen, Audi, and Porsche 3.0 liter vehicles.