While oil prices marked steep losses in June, fuel fell by 2p per litre for the second month in a row.
A litre of petrol now costs an average of 114.71p compared with 116.69p at the start of June, while diesel has fallen 2.2p per litre from 117.77p to 115.57p, according to the latest RAC Fuel Watch report.
The average price at Britain's four major supermarkets was 111.73p for petrol and 112.32p for diesel.
Average fuel prices were 5p lower than in February, meaning a tank of petrol is now around £3 cheaper, while filling up on diesel is around £3.50 cheaper.
Compared with the previous month, a typical 55-litre family car's tank of petrol is now £1.09 cheaper at £63.09, while diesel is £1.21 less at £63.56.
"As wholesale prices have come down in response to a falling oil price retailers have done the right thing and passed their savings on to motorists on the forecourt," said RAC fuel spokesman Simon Williams.
Oil prices plunged six per cent over the month of June, falling as low as $44.23 per barrel.
“But while it’s definitely positive to see pump prices so much lower than they were at the start of the year – especially with the summer holidays just around the corner – the overriding message to motorists has to be one of caution as it seems unlikely that the oil price will stay this low for very long," Williams warned.