Volkswagen made a clear, logical decision at the highest levels of their company on down to the lowest levels to cheat consumers, and the American people. They made a business decision to install a defeat device on half a million of their vehicles that intentionally avoids clean air standards except for while the vehicle undergoes emissions testing.
The best solution is to fine the company so heavily as to permanently shut down the company, and claw back all employee bonuses and pay for those who were involved and criminally prosecute them.