Petrol and diesel contain between five and 10 per cent biofuels, made mostly from wheat, maize and used cooking oil, the price of which has shot up since the war in Ukraine, even more than the cost of regular fuel.
As part of the Government’s net zero drive, E10 petrol was made the standard last summer, while B7 diesel was introduced in 2019.
While the price of petrol and diesel has risen in recent months, the cost of biofuels has increased at an even sharper rate.
The price increases mean biofuel adds at least £8.80 to a full tank of diesel in a family car, and £4.40 to a tank of petrol, according to new analysis from NGO Transport and Environment.
The additional cost amounts to 8p a litre on petrol, 50 per cent more than the Government's recent fuel duty cut.
'Questionable environmental benefit'
Morgan Jones, an analyst at Transport and Environment said: "Not only is this excaberating the food crisis, it's also inflating the cost for drivers - and all for a questionable environmental benefit.
"Pausing the use of crop-based biofuels would be a good start to help reduce fuel costs, but why not turn a pause into something more permanent?"
Boris Johnson was already considering scrapping the mandated use of E10 over concerns that it is adding to the global food crisis by displacing land that could be used to grow crops to feed people. The UK sources around a fifth of the crops for its biofuel from Ukraine.
Land for biofuel for the UK alone could be used to feed around 3.5 million people, according to analysis from the think tank Green Alliance. Halving the amount of biofuel used by the UK, US and EU could free up sufficient grain to replace all exports from Ukraine.
Environmental groups also argue that the use of land for fuel is contributing to deforestation and the loss of species.
The new analysis will add to concerns that the green fuel is adding to the cost of living crisis as petrol and diesel prices reach record highs.
The price of a tank of petrol hit more than £100 this year, prompting warnings of growing forecourt theft and high street losses of millions of pounds.
UK believed to be working with Germany to cut biofuels
Dustin Benton, a policy director at the Green Alliance said: "Biofuels aren’t a very cost effective way of cutting carbon: the Government’s own figures show that it’s cheaper to decarbonise cars by incentivising electric vehicles than by blending in crop-based biofuels."
"In a cost of living crisis, we should choose zero carbon approaches that cut consumer bills."
Craig Mackinlay, the MP from the Net Zero Scrutiny Group, added: "The policy to increase the amount of biofuel mixed in with petrol and diesel is quickly unravelling. The Prime Minister is rightly trying to persuade other governments to scale back their use.
"But here in Britain their increased use appears to be adding a significant cost to filling up the tank with fuel as well as reducing engine efficiency leading to less mpg, just as motorists are already facing unsustainable price rises at the forecourt. The only morally justifiable course of action must be to reverse this hugely harmful policy."
The Prime Minister was blocked by US President Joe Biden in his attempts to push for biofuel mandates to be dropped at the G7 summit over the weekend.
The US is one of the world’s largest producers of biofuel, for which it provides heavy subsidies to farmers.
The UK is now believed to be working with Germany on a potential bilateral action to cut the use of biofuels in the two countries. The move would allow Germany to claim it was providing an extra boost of support to Ukraine, after it faced criticism over its apparent reluctance to supply heavy weapons to Kyiv.