it depends on Distance traveled , Fuel consumption & Fuel type but in general
Average UK new car CO2 emissions fall for 16th successive year to 128.3g/km in 2013.
Advances in new car efficiency enabling emissions from all cars in use to fall, despite increased number of cars in use and distance travelled.
Industry has challenging targets to deliver a 45% reduction by 2020 and will require greater take-up of ultra-low emitting vehicles to meet those targets.