Hey, IV is better than III but V is even better, isn't it? But wait, are Euro V vehicles already available? It's hard sometimes to understand what it really means. Yahoo Autos Italia has a very cool article about the signification of the different Euro polluting rules which, at least, might look confusing (Note: on the other hand EPA rules make categories look more user-friendly, at least for me).
Therefore, let's summarize what the different Euro levels mean for passenger cars:
If the car was sold before the end of 1992, it doesn't have any sort of catalysator and is probably fitted to a carburetor. Of course, carmakers would want us to throw them away and buy newer cars but also governments. You can save hundreds of euros if you trade in one of those cars, which are or are about to be banned from some city centers.
These vehicles must have catalysators and fuel injection. Less polluting and, although still able to run around. The limits in polluting elements were: 2.72 CO g/km (not CO2), 0.97 (or 1.13) Hydrocarbons+NOx g/km and 0.14 g of PM (particulate matter) per km - both for diesel and gasoline engines (save for particulate matters). Your car is Euro I if you find these codes in the papers:91/441/CEE, 91/542/CEE-A and 93/59/CEE
Follow us after the jump for the complete list
[Source: Yahoo Autos Italia & Wikipedia]
Things got tougher for cars in 1997. There were even two different levels of application of these standards. First we have to separate diesels from gasoline counterparts.
Gasoline cars had to emit less than 2.2 CO g/km, and less than 0.5 grams of hydrocarbons and nitrogen oxides combined per km. Diesels had two tiers, depending on the category: 1.0 CO g/km, 0.97 (1.13) HC + NOx g/km and 0.14 (0.18) g of particulate matter per km.
Your car is Euro II compliant if the documentation holds any of these codes:91/542/CE-B, 94/12/CEE, 96/1/CEE, 96/44/CEE, 96/69/CE or 98/77/CE.
Cars immatriculated after Jan 1st 2001. It's the most common tier in current running cars in Europe. For the first time, hydrocarbons were separated from nitrogen oxydes for gas cars as follows:
Gasoline cars: 2.30 CO g/Km, 0.15 NOx g/km and 0.20 non-burned hydrocarbon grams per km
As per diesels: 0.64 CO g/Km of CO2, 0.56 NOx and hydrocarbon g/km and 0.05 g/km of particulates.
A car is Euro III compliant if it was produced according the following rules: 1998/69/CE, 98/77/CE-A, 1999/96/CE, 1999/102/CE-A, 2001/1/CE-A, 2001/27/CE, 2001/100/CE-A, 2002/80/CE-A and 2003/76/CE-A
Current standards in force since Jan. 2006.
Gasoline cars: 1.0 CO g/Km, 0.08 NOx g/km and 0.10 HC g/km.
Diesels: 0.50 CO g/Km, 0.30 NOx and NC g/km, 0.025 of particulates. It makes cars be fitted with particulate filters, although it's yet to be mandatory.
Check your car papers. It's Euro IV compliant if it was built according to 98/69/CE-B, 98/77/CE-B, 1999/96/CE-B, 1999/102/CE-B, 2001/1/CE-B, 2001/27/CE-B, 2001/100/CE-B, 2002/80/CE-B, 2003/76/CE-B
The Euro V is not yet approved but will be mandatory since January 2009 (so you know now that your neighbor might be teasing you). The proposal is:
Gasoline cars: 1.0 CO g/Km, 0.06 NOx g/km and 0.10 HC g/km and 0.005 grams of particulates.
Diesels: 0.50 CO g/Km, 0.23 NOx and NC g/km, 0.018 of particulates.
As you can see, nothing is said about the CO2 levels, although they must be informed in advertising because taxes depend on them. The final restrictions have yet to be determined as averages for a marque range but there's movement and much discussing right now.