The average price of petrol underwent its biggest daily jump in 17 years yesterday – and the milestone £100 petrol fill-up could be reached as soon as tomorrow.  

The cost of a full tank of unleaded for a typical 55-litre family car has now shot up to £99.40, horribly close to the £100 petrol fill-up landmark.  

Forecourt petrol prices went up by more than 2p (2.23p) a litre on Tuesday, according to the RAC, taking the average price to nearly 181p a litre (180.73p).  

It means the cost of a full tank of unleaded for a typical 55-litre family car has now shot up to £99.40, horribly close to the £100 petrol fill-up landmark.  

Diesel prices – which passed the £100 fill-up last week – also continue to rocket. The average price on Tuesday increased by almost 1.5p to yet another record high at 186.57p, pushing the price for a full tank to £102.61.  

Further price increases are expected. The RAC’s data shows that Asda hiked its average petrol price nearly 5p a litre yesterday – a new record for a single day.  

Meanwhile the average petrol price at the big four supermarkets is now 173.37p, while diesel is 182.38p. A litre of unleaded is now more than 7p cheaper at a supermarket – significantly more the normal 4p price gap – and RAC expects the other supermarkets to increase their prices today to close that gap as Asda is traditionally the cheapest retailer.  

RAC fuel spokesperson Simon Williams said the rises were “unprecedented” and that the peak was likely still to come, with the average price of diesel heading towards £2 a litre. 

But he added: “The cost of wholesale petrol unexpectedly dropped around 5p a litre on Tuesday. If this price is maintained in the coming days, it could stem the flow of daily record petrol prices.”