As if Volkswagen isn’t facing enough challenges, another obstacle to fixing its out-of-compliance diesels may come from an unlikely source: uncooperative customers.

The new worry stems from the realization that bringing the 2.0-liter diesel engine into emission compliance will negatively affect driving experience and fuel economy. This may make owners hesitate to have the repair done, and there are very few areas that can enforce the recall.

“There are two apparent ways to [repair the cars], and owners who value performance, fuel economy, and trunk space won’t like either,” noted Alex Davies on as he lists the two likely options for VW.

The first is a software fix – retune the settings in the engine control module to operate as if it’s always being tested.

“The downside here is that to achieve the drastic drop in NOx emissions, the cars in test mode sacrificed some fuel economy, or performance,” said Davies. “Just how much is hard to say, but any drop in torque – one great thing about diesels is how they accelerate off the line – will not make drivers happy.”

SEE ALSO: Volkswagen To Begin Recalling Over-Emitting Diesels in January

An alternative solution for Volkswagen is to install components that use urea to break down harmful pollutants into water and nitrogen. This type of system is currently seen on diesels from Mercedes and BMW, but wasn’t used by Volkswagen in its 2.0-liter diesel engines.

“The big ‘advance’ from VW was the ‘clean diesel’ technology that supposedly made the whole urea thing unnecessary on its smaller cars, like the Beetle, Jetta, and Audi A3 – the very models being recalled because they don’t meet emissions standards under real-world driving conditions,” Davies explained.

Using a urea system would be costly and time consuming for Volkswagen, and it’s also likely to leave owners with a bad taste in their mouth.

“Not only do you have to spend an afternoon with your local dealer, you have to make room for the tank,” noted Davies. “That could mean sacrificing cargo space or giving up the spare tire.”

Few regulations across the U.S. exist that will require owners get their VW’s fixed. According to Automotive News, here’s how it brings down across the country:

  • Nationally: No federal law or EPA mandate is in place forcing owners to cooperate with an emissions recall. “The EPA has the authority to order VW to recall the vehicles,” noted Automotive News, “but its authority to compel consumers to get their cars repaired is limited.”
  • California: This is the only state that will prevent a car’s registration from being renewed if the owner hasn’t complied with an emission recall notice.
  • States with emission test requirements: While most states require an annual or biennial emissions test, the EPA said that only 17 states will demand that owners show they have complied with an emission recall before they can conduct the test. Many states, such as Texas and Illinois, do not require diesel engines to undergo emissions tests.