Volkswagen’s stunning admission that it sold diesel-powered cars that intentionally faked emissions testing results has left many of their owners — who thought they were buying fuel-efficient and environmentally friendly vehicles — angry and feeling betrayed.

The deception could prove a major threat to Volkswagen’s reputation in the United States and could break the trust that the German automaker had cultivated with car owners over the years. It could also have lasting consequences for the future of diesel-powered technology championed by Volkswagen, which has been seeking to make a comeback in the United States.

On Friday, the Environmental Protection Agency announced that it would order Volkswagen to recall nearly 500,000 vehicles in the United States because they were equipped with software that allowed them to evade emissions standards for reducing smog during testing. No recall has been ordered yet, however, until Volkswagen can outline how it intends to fix the problem.

But whatever the technological solution, it will most likely mean reducing the performance, drivability or fuel economy of cars to meet emission goals.