A litre of the fuel costs an average of £1.32 at UK forecourts, according to recent Government statistics.
It has not been that expensive since September 2013, according to analysis by the PA news agency.
The price of petrol has risen for 32 consecutive weeks.
Diesel had increased in price for the same number of weeks until it fell by a fraction of 1p to £1.34 per litre this week.
Steve Gooding, director of motoring research charity the RAC Foundation, said: "It looks like our staycations have just got that bit more expensive.
"On top of huge hikes in the cost of holiday accommodation across the UK, motorists filling up the car for their family getaway will be faced with petrol prices at an eight-year high.
"There's also the chance of worse to come with oil prices continuing to nudge upwards."
Mr Gooding added that the rise in petrol prices means it was "no surprise" that more than one in 10 new cars sold in June were pure electric.
He continued: "With the oil price continuing to rise, and pump prices not far behind, it seems more and more people are doing the sums and finding that despite high purchase prices, the running costs of battery-powered vehicles really are too low to ignore."
Average fuel costs were just £1.05 per litre of petrol and £1.12 per litre of diesel in May 2020.
Since then, the cost of filling up a typical 55-litre car has risen by around £15 for petrol and £12 for diesel.