Motorists have begun 2018 paying the highest price for petrol since the end of 2014, data from RAC Fuel Watch has revealed.

An analysis of fuel prices for December shows the average price of unleaded increased for the second month running – this time by nearly half a pence from 120.66p to 121.11p, while diesel went up from 123.06p to 123.46p (0.4p).

A litre of petrol is now at its highest price point since 2nd December 2014.

The price of both fuels has increased substantially from July, when petrol was at its cheapest point of the year at 114.33p a litre, and diesel cost 115.02p a litre.

This means a tank of unleaded for an average 55-litre family car now costs £66.61 – £3.73 more than it did in July.

For diesel, a fill-up now stands at £67.90 – £4.64 more than in the summer.

Looking further back, the RAC says current pump prices are a far cry from early 2016 when both fuels averaged 102p a litre. But more positively, they are still considerably cheaper than April 2012 when the UK average prices of petrol and diesel reached record highs of 142p and 148p a litre respectively.

The RAC says price rises have been driven by the increased cost of oil, which is now at its highest level since May 2015, having risen by 3% in December.

RAC fuel spokesman Simon Williams said: “Sadly, December was the month oil reached its highest point for over two and a half years – something which motorists are now feeling the effect of at the pumps.

“On a brighter note, the shutdown of the North Sea Forties pipeline did not cause the price of oil to increase as many expected. It had been feared this would lead to petrol and diesel going up in the run-up to Christmas, but luckily for drivers global oil production was not negatively affected as a result.

“It’s hard to see pump prices getting much cheaper in the early part of 2018. Unfortunately, the good times of lower cost fuel appear to be over and it’s probably now far more likely that we will see them going up as OPEC’s oil production cuts are starting to have the desired effect of reducing the global oil glut and pushing the barrel price higher.”