Opposition parties are rallying behind a campaign to scrap August's planned 3p hike in fuel duty.
Forty MPs have backed the SNP-led campaign against the hike, which will culminate in a parliamentary vote on the issue near the end of the month.
Around half come from parliament's fringe parties and there are only four coalition backbenchers currently in support.
But the SNP's Treasury spokesperson Stewart Hosie remains optimistic that the government can offer another U-turn after changing its mind on pasties, caravans, skips and the charity tax.
"Politicians are throwing aside party differences and uniting on this crucial issue to help boost our stagnating economy," he said.
"The campaign is growing fast both inside and outside the parliament... There is no excuse not to listen to the hundreds of thousands of people who are calling for an end to this highway robbery."
Britain, which has the highest fuel taxes in Europe, sees 81.5p of every litre of petrol sold going to the Treasury in fuel duty and VAT.
The Road Haulage Association's chief executive Geoff Dunning said it was "great news" that the campaign against the fuel duty increase was attracting so much political support.
"We must see the August rise abandoned and we are calling on our members to contact their MP as a matter of extreme urgency in order to swell the numbers of those at Westminster who are prepared to support the cause," he said.
Further support for the campaign could be possible among Tory MPs who have not yet signed the motion.
Among them is Harlow MP Robert Halfon, who called for an end to fuel duty hikes in a comment piece for politics.co.uk last November.
"To his credit, George Osborne has taken major steps to help, including a 1p cut in fuel duty and abolishing Labour's 'tax escalator'," Mr Halfon wrote.
"But we urgently need to do more. We need no new fuel taxes in this parliament."
Outspoken Tory backbencher Nadine Dorries has also called on the chancellor to scrap the 3p increase.
She said: "Many families are now on the cusp of deciding whether or not they can keep the family car. I have constituents who are selling up the house they waited years to buy because the cost of transport and petrol has forced them back to the city."