Latest research has revealed the scale of the premium companies pay for fuel in the UK, with other European countries up to 35 per cent cheaper for both petrol and diesel.
Average prices for petrol in the UK were 74.5p per litre during October, with diesel costing 77.3p per litre. Of that, 76.4 per cent of petrol cost goes in tax and 74.2 per cent of diesel.
By contrast, Austria charges the equivalent of 56.8ppl and 47.5ppl respectively, while Spain charges just 50ppl for petrol and 44ppl for diesel.
But even with such massive discounts compared to the UK, Europe is expensive compared to the United States, where petrol is the equivalent of 24p a litre and diesel costs 26ppl.
The findings, released by AA Business Services, were revealed as the head of one fleet raised concerns that diesel prices in the UK were too high.
David Hekelaar, managing director of Viking Standby, based in Montrose, Scotland, said: 'Prior to the recent reduction in costs, unleaded and diesel fuels were at a similar price. But currently diesel is approximately 5p per litre more expensive than unleaded. I do not think the cost reduction in crude oil is being reflected in a lower cost of diesel.'
Currently, only Switzerland charges more for diesel than petrol, with every other country offering a healthy discount on the fuel.
A spokesman for said: 'The difference between petrol and diesel is because they are two different products, with different costs and a different market, therefore the price of the fuel has not come down as much as unleaded,' he said.