Travelling in Europe - Euro 6

I am still deciding on what van to purchase, obviously now most people would say that to not have a Euro 6 compliant van is restrictive. I am just enquiring about how true this is. I would like to travel around France and read that you can’t drive around French cities without the Euro 6 van but I just wanted to find out if anyone has been able to travel into the main cities without a Euro 6 van? And if so, which cities?

Greetings & Welcome!

I’m in the USA and unfamiliar with the laws over there, but at least wanted to welcome you aboard.
:four_leaf_clover: :grinning: