U.S. regulatory agencies still haven't approved a plan to modify the 482,000 Volkswagen 2.0-liter TDI diesel cars equipped with "defeat device" software used to circumvent emissions laws.

It will likely cost VW billions of dollars to update the delinquent cars, and it may not be practically possible for certain models.

That prompted 45 environmental leaders and Silicon Valley executives, including Tesla Motors CEO Elon Musk, to suggest that VW shouldn't bother.

DON'T MISS: Ignore VW Diesels, Make Company Sell Electric Cars: Tesla CEO Musk, 44 Others

In a letter addressed to Mary Nichols, head of the California Air Resources Board (CARB), they advocated forcing Volkswagen to build zero-emission vehicles instead.

CARB has to sign off on any proposed recall program for the VW diesels, as does the U.S. Environmental Protection Agency.

But forcing VW to build more electric cars won't really address the issue of its emissions cheating, says the environmental justice community in a letter of its own.

2015 Volkswagen Passat TDI

2015 Volkswagen Passat TDI

Signed by 15 leaders of environmental, conservation, and health groups, the rebuttal to the don't-repair-them letter insists that Volkswagen must recall all affected diesel cars and counteract the excess pollution they have caused, plain and simple.

The original letter suggested releasing VW from its obligation to fix non-compliant diesels, and instead directing it to "greatly accelerate its rollout" of zero-emission cars.

While it supports CARB's work to "transition California's transportation system to a zero-emission vehicle future," the signers from environmental justice groups feel the Silicon Valley proposal fails to address the damage already done by the VW diesels.

ALSO SEE: How Will VW Fix My Diesel Car, And When? A List Of All Models

That proposal "does not address the real health impacts" caused by the non-compliant diesels, the group says.

It also "offers no remedy to the purchasers of the defective VW diesel vehicles," who often bought their cars because of a perceived environmental benefit, the letter notes.

Rather than forgive Volkswagen's transgressions, the signers call for a full investigation, and prosecution to the fullest extent of the law.

2015 Volkswagen Golf TDI

2015 Volkswagen Golf TDI

Vigorous prosecution is essential to "deterring this kind of intentional and egregious violation of laws that protect public health," the letter says.

Yet there are still ways to use punitive measures against VW to promote electric cars, the proposal suggests.

It calls for using penalties collected by CARB to fund programs that help increase the deployment of zero-emission vehicles in lower-income communities.

MORE: VW Gets More Time To Figure Out TDI Diesel Emission Update

Volkswagen should also be forced to pay for pollution-mitigation measures equal to "several times" the total amount of excess emissions produced by its diesel vehicles.

And to ensure that these measures have a meaningful impact, VW should also foot the bill for more extensive near-road air quality monitoring, says the group.

CARB received a proposal from Volkswagen for modifying the 482,000 2.0-liter TDI cars in late November, but recently decided to extend its deadline to reject or approve that proposal.

No details of the proposal have been made public, but VW can't proceed with a recall unless CARB approves it.

[hat tips: Bruce Mirken, Felix Kramer]


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