HI Orla,

If the car was registered from 2008 on then it's not the engine size that matters, it's the CO2 rating, and that varies massively from car to car. A diesel 1.4 will almost always emit less CO2 than a 1.4 petrol engine so will be cheaper to tax for cars registered from 2008 on.

Now, if the car was registered before that, and its engine size is between 1,301- and 1,400cc, it will cost €385 a year to tax, regardless of the fuel type.