Volkswagen has a lot of explaining to do.
Since it was revealed in September that the company installed "defeat device" software on diesel cars that allowed them to cheat on emissions tests, VW has been slow to discuss what it plans to do with the affected cars.
The carmaker still hasn't confirmed when it will begin a recall of the 482,000 TDI models equipped with EA189 2.0-liter four-cylinder engines in the U.S.
DON'T MISS: VW Buybacks, Payments For Hard-To-Fix Diesels Will Cost Billions
But Volkswagen is prepared to begin a recall in Europe, where emissions standards are somewhat less strict.
It even released a video in which it tries to explain the current situation, and how it plans to remedy it.
In it, a starkly robotic narrator explains how diesel engines work, the various methods used to limit the pollution they produce, and the nature of the "defeat device" software.
2015 Volkswagen Golf TDI
SCR systems use urea fluid injected into the exhaust stream to eliminate pollutants.
While vehicles already equipped with this hardware may only require software updates to obtain compliance, other cars may not be able to meet emissions standards without them.
ALSO SEE: How Will VW Fix My Diesel Car, And When? A List Of All Models
But this could cost thousands of dollars per car, and push recall work into 2017. Analysts have expressed skepticism over whether such extensive and expensive work is justified in cars as much as seven years old, and claim buybacks may be a better option.
The video goes on to explain the nature of the "defeat device" software, which allowed cars to detect the conditions of a laboratory test--and temporarily lower emissions to legal levels.
In real world driving, though, these levels were ignored. Certain models were found to emit up to 35 times the amounts of nitrogen oxides allowed under Environmental Protection Agency (EPA) rules.
2015 Volkswagen Golf TDI
Cars with 2.0-liter and 1.2-liter versions of the engine will get software updates, while 1.6-liter versions get the software and modifications related to the airflow sensor.
MORE: VW Gets More Time To Figure Out TDI Diesel Emission Update
Meanwhile, U.S. owners are stuck in limbo while the EPA and California Air Resources Board review a proposed fix submitted by Volkswagen in November.
In addition to the EA189 cars, about 85,000 VW, Audi, and Porsche vehicles in the U.S. with a separate 3.0-liter V-6 powertrain were also found to have "defeat device" software.
No timeline for a recall of these vehicles has been discussed so far.
[hat tip: Brian Henderson]