Petrol now costs an average of 154.5 cent per litre, down 2.9 cent since June.
The fall in price for diesel was even greater: it now costs on average 144.4 cent per litre, a drop of 3.6 cent.
Fuel prices have continued to fall since March of this year; in the last four months petrol has fallen by 7.6 cent per litre and diesel by 10.7 cent.
"While a drop in fuel prices is always welcome, filling up in Ireland is still extremely expensive," said Conor Faughnan, Director of Policy at the AA.
"Tax plays a huge part in the cost of fuel in Ireland; the service station owners don't reap much of the rewards for increased prices - most of what you're paying is in tax."
Irish drivers pay out significantly through a combination of excise duties, including carbon tax and VAT, as over 57% of the price of both diesel and petrol is tax.
A typical Irish car doing typical Irish mileage will use 1,800 litres of fuel annually or 150 litres per month. At current prices, that means drivers will pay €231.75 this month for petrol, of which €132.10 is tax.