State and federal environmental regulators announced Monday they had approved modifications to illegally polluting Volkswagen, Audi, and Porsche SUVs fitted with VW Group's 3.0-liter V-6 TDI turbodiesel engine

The EPA and California Air Resources Board sent a letter Friday to VW announcing the approved modifications for the 3.0-liter TDI models.

The fixes apply to 2013-2016 Volkswagen Touaregs, 2015 Audi Q7s, and 2013-2016 Porsche Cayenne SUVs that were equipped with diesel engines.

DON'T MISS: Fix for Audi, VW, Porsche V-6 diesels closer to approval: report (May 2016)

Altogether, the updates apply to roughly 38,000 vehicles, all of them fitted with a second-generation 3.0-liter V-6 TDI engine.

Vehicles sold from 2010 through 2012 fitted with an earlier version of the 3.0-liter diesel V-6 were treated separately.

The approved updates mean that VW likely won't have to buy back those vehicles from owners and could save on additional penalties from environmental agencies.

2015 Porsche Cayenne Diesel

2015 Porsche Cayenne Diesel

Reuters reported that the approval may save the automaker more than $1 billion, although VW has reportedly already spent more than $25 billion for the fiasco in the U.S. so far. 

Regulators said that modifying the 2015-2016 Touaregs and Cayennes will require only a software update, while the other vehicles may need a software update and hardware modifications.

READ THIS: How VW's 3-liter V-6 TDI diesel cheat worked (Apr 2016)

A VW spokeswoman didn't immediately comment on what those hardware modifications will be.

Volkswagen is required to notify owners before the end of October that their vehicles can be modified.

2014 Volkswagen Touareg TDI

2014 Volkswagen Touareg TDI

What remains uncertain is how or whether Volkswagen will be able to modify other models equipped with the same engine or, in two cases, SUVs fitted with an earlier 3.0-liter diesel.

Those cars include the Audi A6, A7, A8, and Q5 models, along with older versions of the Volkswagen Touareg and Audi Q7.

CHECK OUT: Want to buy a used, updated Volkswagen TDI diesel car? Your VW dealer gets first dibs

Last year, regulators rejected a proposed update for those cars submitted by VW in February 2016.

A spokeswoman for Volkswagen said that the company is working "with our regulators to develop approved solutions for the remaining 3.0L TDI V6 vehicles as quickly as possible."


Follow GreenCarReports on Facebook and Twitter.