Quite simply politics & bankers have f*c!ed it.
We all have a major can of worms that cannot be rectified.
Think about it this way.....
There has to be a complete change of wash from the top down. But that never happens due to corrupt backscratching.

The whole system has undermined the MOT emissions test.

If we could have a true free market it would develop clean engines through freewill not by fudging latest tailpipe standards with Pig Piss.

The way diesel engines are setup now gives a short term tailpipe roses & petals but EGR cycles & regen counts per trip are hammering the engine oil & clogging intake systems.

Have Had diesel vehicles pass the MOT emissions but then a day or two after had running issues & faults after the MOT due to the rev cycle for the gas analyser causing different pressures in the engine due to partcially blocked DPF

If you seal a turd in a balloon you can't smell it but when the balloon bursts you have BIG JOB on your hands.

This guy tells you what a paradox the DPF cycle is if customers don't service their vehicles.

https://www.youtube.com/watch?v=fNO-oUHmKXU