Dont know this year. On previous visits to Ireland the cost in cents was the same as we pay in pence. ie. 89 cents per litre in Ireland while in London it was 89p per litre. Considerably cheaper in Ireland. If you go fill up in Dublin, a lot cheaper than out in the country. Avoid the north which used to be cheap but now is very similar in price to England.
I went to southern Ireland in June. It averaged around E1.01 per litre, converted its about 0.72p. Northern Ireland should be similar to mainland England.