///Even if (this time) it might (possibly) be true, it only applies to brand new engines in 'testbed' conditions. ///
That applies to all engines whether diesel or petrol. All engine emissions depend on maintenance of a high standard. I'm all for 'on the spot' test and requisite fines to 'remove' the offending vehicles.
I decided on a diesel for me, because of low Vehicle Excise Duty, good fuel economy for my lifestyle and use. Now, I'm getting pilloried for an apparently 'filthy' engine, how times change.
Before you ask, the same car with a petrol engine has the same VED rate and is about 30% less fuel efficient. The engine is just isn't as good either, I drove both before deciding.
Don't worry, those with petrol engines will be next in line for the 'treatment'. I can foresee anyone with a 1600cc engine or above getting heavily taxed for the privilege, much much more than they are now.
Hybrid/Electric may help for a few years as a stopgap, until such time as EV's get a better range on batteries. Also depends on more clean electric production and we are a long, long way from achieving that.