Dual fuel cars are currently not allowed to enter the tunnel, and ACFO chairman Tony Leigh revealed at Fleet News' Hit for Six conference that he had written to the authorities on behalf of fleets to explain why there had been no lifting of the ban.
Chris Coombes, deputy chief fire officer of the Leicestershire Fire Service and an advisor on tunnel safety, said the situation was ridiculous and needed to be investigated.
He said: 'I travel through the tunnel regularly and I am amazed you can take caravans through, with LPG canisters strapped to the front, but you cannot take a dual fuel car through.
'There is an explosion danger with LPG as with any fuel. And look at the case of gas filled struts, which explode spectacularly, with metal flying everywhere.'
The dual-fuel ban has been in place since the tunnel was opened in 1994, amid fears that a fire could lead to gas tanks exploding in the tunnel.
However, the chances of the ban being lifted appear remote, at least for the moment.
A spokesman for Eurotunnel said: 'Conditions in the tunnel are different to the open road, and we are not completely satisfied that all LPG conversions are completely safe.'
Although the company has no problem with dual fuel cars from manufacturers such as Vauxhall or Volvo, it cited the findings of Birmingham Trading Standards, which found that 19 out of 20 conversions not carried out by LP Gas Association-approved installers had potentially dangerous faults.
The spokesman added: 'At the moment we cannot differentiate between one or the other. It is not a stage we are at yet. We are monitoring the situation.'