Seriously- the Jetta TDI made 11% less power[1] in compliance mode. This isn't about the regulations being hard to meet, it's about flagrantly disregarding the EPA. It's about how pathetically toothless the EPA is, that they didn't have the funding or reach to discover this and instead college students figured it out.
[1]: https://jalopnik.com/heres-how-much-horsepower-volkswagens-l...