A litre of petrol reached an average of £1.17 in the UK on Monday, Government figures show.
This is higher than at any point since December 2014.
Diesel car drivers are also feeling the strain on their wallets, with an average price per litre of £1.20, last seen in July 2015.
The data from the Department for Business, Energy and Industrial Strategy shows that petrol and diesel prices rose by more than three pence per litre in the past four weeks.
The increase in pump prices follows a 24 per cent rise in the price of oil, from 45 US dollars (£37) in mid-November to 56 US dollars (£46) by the end of December.
This was driven by a deal between Opec and other major oil producers in November to curb output.
Steve Gooding, director of motoring research charity the RAC Foundation, said: "For the 17 million people or so who commute by car the return to work will have come with a nasty surprise. With pump prices up again, the cost of an average tank of fuel is around £10 more today than it was a year ago.
"Transport is the biggest area of household expenditure and many drivers will be asking the same question as those rail travellers just hit by big fare increases: at what point does the journey to work start looking like it just isn't worth it?"
Rail fares in Britain rose by an average of 2.3% on Monday.