It is an interesting idea and they have proposed to start with older commercial vehicles. I am not sure that Paris officials have the authority to impose the ban. It contravenes the Euopean Community rules relating to free movement of goods and trade so is likely to be challenged at the European Court of Justice at the Hague. This may well have more to do with announcing vote catching policies about pollution rather than a serious attempt to ruin the Paris tourist trade (I regularly drive my pre 2011 car to Paris via the Channel Tunnel) Faced with the prospect heavy fines the politicians may well back off claiming that it is not their fault that they cannot implement this policy. But that would be after the election.

So Paris is banning all old cars ... except for the old cars they like to see on the road.

That's like a dance club banning everyone over 25 ... except for friends of the owner, it's an arbitrary ban with an even more arbitrary and subjective loophole. In America, a rule like that would be called 'an attempt to legalize discrimination,' and the person or persons who proposed or supported that rule would be called ... I don't use those words in a public forum, but you all know which ones I'm talking about, they start with the rude names for certain anatomy parts and get more offensive from there.