For the moment in Italy we pay annual tax based on power, not on the emmisions. I hope the Italian politicians don't get wind of this system.
As for new cars they have just introduces an "Ecotax based on CO2 emissions. This is paid only on the first matriculation.
Emissioni di CO2 (ciclo NEDC) Ecotassa all'acquisto
161-175 g/km 1.100 euro
176-200 g/km 1.600 euro
201-250 g/km 2.000 euro
oltre 250 g/km 2.500 euro
I have used the code tag to get the table to line up.