Metropolitan Police drivers will not be refuelling their cars with premium "superfuels" after Scotland Yard transport bosses said they "offer no discernible benefit" over standard products.
They added that the use of public money to pay for the extra cost of superfuels was not justified.
Staff could choose the cheapest fuel available, director of transport services Nigel Jakubowski stated in documents submitted to the Metropolitan Police Authority (MPA).
Mr Jakubowski said: "It is also proposed that users are prevented from using 'super' fuels that offer no discernible benefit over standard fuels but typically cost more than five pence per litre more."
As many as 5,442 road vehicles - from hybrid cars and motorcycles, to armed response vehicles, coaches and specialist lorries - are used by the Metropolitan Police.
Officers clocked around 65 million miles on 4.5 million litres of unleaded fuel and 8.8 million litres of diesel in 2008-09.
The ban came as senior staff signed a new contract for vehicle fuel cards. The two-year deal would give drivers more flexibility and allow them to take advantage of cheaper supermarket forecourts, senior staff said.
Last year, a report by consumer magazine Which? claimed that superfuels were a "waste of money", drawing opposition from fuel providers.
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