One of the main considerations for buying a used car is economy and efficiency, particularily if the car has been registered post 1 July 2008 when the new motor tax rates were brought in. Cost of ownership is decided by many factors, fuel type (See Petrol or Diesel), engine size and efficiency.

With the motor tax (often called road tax) changes brought in by the Irish Government during July 2008 (later backdated to January 2008), the efficiency of a used car became an even bigger factor than before. Motor tax rates are based on the carbon dioxide emmisions of a particular car, with environmentally friendly cars being rewarded with a low road tax cost and high emmission cars being punished. Prior to these new measures, motor tax rates were judged on engine size.

Cars registered before 1 January 2008 are still charged are the old rate of road tax based on engine size, while new cars are banded depending on C02 emmissions/grams per KM.

	Band	CO2 emissions-gm per km	Annual	Half-year	Quarterly
	A	0 -120g	104	57	29
	B	More than 120g/km up to and including 140g/km	156	86	44
	C	More than 140g/km up to and including 155g/km	302	167	85
	D	More than 155g/km up to and including 170g/km	447	248	126
	E	More than 170g/km up to and including 190g/km	630	349	177
	F	More than 190g/km up to and including 225g/km	1,050	582	296
	G	More than 225g/km	2,100	1,165	593

Cloghran Car Sales.com offer a wide range of used cars that have been registered post 1st July 2008. Mid size diesel cars are now just as environmentally friendly as small sized petrol cars.