In Germany too your gasoline car has to fulfill some requirements AND has to get a vignette too, to be able to enter those zones legal.
It depends a lot on the spec of the diesel vehicle. Starting from Emissionstandard Euro4 upwards you can enter most zones in europe. But yes, sometimes you need to optain a vignette /register your car.
Looking at this, it is more the age of the vehicle, who counts, not if gasoline or diesel. As Overlander you has to watch the reqirements per country and city, but that is not too new.
At 2010 in Laos you was able to use left or right roadside for parking, depending on the weekday, written in their language - nothing what is easy to understand as a foreigner - so nothing really new on international journeys.
We did had to choose too at the end of 2021, for our new family capable vehicle for the following internatioal journeys - and did opted for an diesel. The Euro6temp Emission Standard, will let us visit citys at least for the next 12 years, we did hope. I love the Hubb - i`m shure that we will look back and discuss about at 2033
Surfy