Comparing all the cars registered at the end of 2013 with all those registered at the end of 2008 shows that the average CO2 emissions across the stock of cars as a whole fell by 7%.
Mae cymharu’r holl geir a drwyddedwyd ar ddiwedd 2013 gyda’r holl geir wedi’u cofrestru ar ddiwedd 2008 yn dangos bod cyfartaledd allyriad CO2 ar draws y stoc o geir ar y cyfan wedi disgyn 7%.