Motoring group RAC today accused Britain’s ‘Big Four’ supermarkets Tesco, Asda, Sainsbury’s and Morrisons of overcharging drivers at petrol pumps.
Though fuel prices fell for the fifth straight month in March, with a penny coming off petrol and 4p off diesel, RAC argues diesel prices should have fallen much further.
Wholesale petrol and diesel prices were almost identical during March but the average price of diesel at the pumps was 162.9p compared to only 146.5p for unleaded, a difference of 16.4p.
The average retailer margin on a litre of diesel in March was 21p, according to RAC.
This is three times more than usual and also three times the average margin for a litre of petrol in the same month.
If diesel prices at the pumps had come down in line with wholesale prices a litre would cost only 152p, calculates RAC.
Of the big four supermarkets, Asda sold the cheapest petrol during March, at 142.7p a litre, and Tesco the cheapest diesel at 159.6p.
But a small retailer in Shropshire managed to sell both petrol and diesel at just 142.9p a litre, reflecting the wholesale prices of both for the month.
RAC said a lack of competition in the UK meant supermarkets could exploit motorists.
In Northern Ireland, where petrol and diesel are respectively 2.5p and 10.2p cheaper than the UK as a whole, the Big Four supermarkets make up only 28 per cent of the forecourt market compared to 43 per cent for the whole of the UK.
Londoners pay 1.3p and 2.1p more for their petrol and diesel respectively than the average for the UK as a whole.
Simon Williams, RAC fuel spokesman, said: “We hope the Competition and Markets Authority is paying close attention. The situation in Northern Ireland shows just how much diesel should really be being sold for.”
“If a small retailer at Whitchurch in Shropshire can afford to sell both petrol and diesel for just 142.9p a litre, then there’s surely no reason why the big four supermarkets can’t as well”, he added.
The Competition and Markets Authority declined to comment but launched an ongoing investigation into fuel prices last year.
City A.M. also approached the Big Four supermarkets and the British Retail Consortium for comment.