It's been more than five months since the U.S. Environmental Protection Agency (EPA) announced Volkswagen's use of illegal "defeat device" software in diesel cars in mid-September.

But Volkswagen appears no closer to beginning a recall of the affected cars--leaving owners of almost 600,000 diesel vehicles deeply frustrated.

And the Federal judge overseeing hundreds of class-action lawsuits against VW believes that is now unacceptable.

DON'T MISS: California Rejects VW Diesel Fix Plan: 'Gaps,' 'Lacks Detail'

U.S. District Court Judge Charles R. Breyer told Volkswagen's lawyers at a hearing in California Thursday that the company needs to report back to him by March 24 on plans to address the "defeat device software," as well as the status of negotiations for a settlement with owners.

He said six months is enough time for VW to find a fix for its diesel cars, the Associated Press reported.

The judge noted that every additional day the affected cars remain on the road, they not only produce excess pollution, but owners remain stuck with cars they may not be able to sell.

2015 Volkswagen Golf TDI

2015 Volkswagen Golf TDI

On-road testing found that certain TDI models equipped with "defeat device" software emit 35 times the legal levels of nitrogen oxides.

Volkswagen has repeatedly stressed that the cars remain safe to drive, and that owners should continue doing so until a recall begins.

ALSO SEE: VW Submits V-6 Diesel-Update Plan For Audi, Porsche, VW Models

Breyer also believes that setting a 30-day deadline will spur VW to come up with a solution.

"I've found the process is a function of how much time people have available to fill," he said.

2013 Audi Q7 TDI S Line

2013 Audi Q7 TDI S Line

Volkswagen submitted a plan for the 482,000 affected 2.0-liter four-cylinder TDI models in November to the EPA and California Air Resources Board (CARB).

But the two regulatory agencies rejected it last month, with CARB saying the proposal lacked detail about the effects of the modifications on the cars' fuel economy and performance.

MORE: Volkswagen Hires Kenneth Feinberg To Set Payments For U.S. Diesel Owners (Dec 2015)

VW hasn't announced a new plan for the 2.0-liter cars yet, but earlier this month it submitted another proposal addressing the 85,000 cars equipped with a separate, 3.0-liter V-6 powertrain.

That proposal--which just barely made a deadline set by regulators--is still being reviewed by CARB and the EPA.

Regarding yesterday's decision, VW Group of America's Jeannine Ginivan told Green Car Reports only, "I am unable to comment on the date specifically other than to say we are working with the agencies."


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