The UK is now one of the most expensive places in the continent to fill up, and calls for the government to do more to help are said to be "falling on deaf ears".
The UK has done less to ease the burden of high petrol prices than other countries, the RAC has claimed.
Figures suggest that - in a league table of European governments that have taken action to slash petrol taxes - only Luxembourg performed worse, with 11 countries offering more generous relief.
The 5p per litre reduction implemented by the UK in March is dwarfed by fuel tax cuts enjoyed by drivers in countries such as Germany (25.1p per litre), Italy (21.2p per litre), Portugal (16.2p per litre), the Netherlands (14.7p per litre) and Ireland (14.5p per litre).
Governments in France and Spain have introduced discounts at forecourt tills worth about 15p per litre and 17p per litre respectively.
Some fuel retailers, including TotalEnergies in France and BP Spain, have price reductions worth up to about 33p per litre.
UK petrol prices finally started falling in recent days after pressure on retailers to reflect a drop in wholesale costs which began seven weeks ago.
At 186p per litre, costs are much higher than across the EU - with the exception of Denmark (also 186p) and Finland (190p).
Drivers in France pay around 23p per litre less than those in the UK.
Of the 15 European Union states that have not taken steps to lower pump prices since March, all but six already charge less fuel duty than the UK.
It is a similar picture for diesel, with only Croatia introducing a smaller fuel tax cut than the UK, and only one European Union member, Sweden, having a more expensive average price.
RAC fuel spokesman Simon Williams said the analysis amounted to an "uncomfortable truth" for the UK government - that compared to other European countries, it's "pretty much done the least to support drivers through the current period of record high fuel prices".
He added: "The result is the UK being one of the most expensive places to fill up and putting it above other countries that have historically charged more for fuel than UK retailers do, including France and the Netherlands.
"The cost-of-living crisis shows no signs of coming to an end anytime soon, and it's frustrating that repeated calls to the UK government for more support are falling on deaf ears.
"UK pump prices might be finally starting to fall, but the reductions so far are too little and too late, given the massive wholesale price drops retailers have been benefiting from for nearly two months."
Impact of war
Fuel prices were already rising before Russia's invasion of Ukraine in February, but the impact of the war has exacerbated the situation.
A reduction in the use of Russian oil has increased demand from other producers, resulting in higher prices.
Protests have been held in the UK, with convoys of vehicles driving slowly on motorways.