I'm taking my S-Max to France. It's one of the last Mk 1's - specifically a Titanium X Sport Auto TDCi 163.  On the few occasions I drive into the London ULEZ, I'm charged £12.50 per day for being "non-compliant".   The V5C mentions 'EURO5' which I believe means my car emits less than 0.18g/km of NOx gases.   My V5C shows my NOx emissions are 0.175 so I just creep in.  I thought London ULEZ non-compliance was for EURO6 vehicles which I assume emit more NOx than EURO5 vehicles.  So why is my S-Max deemed to be non-compliant? 

I've just ordered my Crit'Air sticker for the French trip and have declared my car is EURO5.  The sticker has cost me €4.91 which includes postage, and it covers me for driving in any city which has a low emissions zone and for the lifetime of the car.  I'm staggered at how cheap this is compared to the £12.50 each time I drive into London.

Or am I comparing chalk & cheese?

 

Your numbering is the wrong way.

Euro 6 emissions are tighter than Euro 5.  They pretty much all needed Adblue or a NOx cat to meet Euro 6 standards.  That's why Euro 6 diesel is free for ULEZ, but nothing below it.  

Petrols have to be minimum of Euro 4, which may be where the confusion comes from.

 

No experience with the French system but that sounds more like a box-ticking fob-off than actually improving air quality in cities.

We have CritAir and Umwelt stickers and they usually cover cities but not motorways that pass through them.
There may be times when certain levels are not allowed in the city centre but we have never needed to be aware of or noticed any prohibitions on our travels (but that's not to say the schemes haven't changed or been extended)
As said the charges in UK are spreading and high if you have to pay them, a bit like the various tunnel and bridge tolls which increase regularly for crossings which it appears will never be paid off.
My worst is the disgusting dirty tunnel that is the Tyne TT2 which is a private road owned by the local authorities. Absolutely dire when compared to almost any sparkling tunnel in the EU tolled or not (rant over!)