The FairFuel UK campaign led by former Top Gear presenter Quentin Willson has found the UK now has the highest duty on diesel in the EU and is behind only Sweden for petrol taxes.
Mr Willson pointed out that if the Chancellor agrees to their demands on Budget Day, March 19, the UK would drop to 18th place in the tax tables for petrol and 9th for diesel.
He said: "Having the highest duty for diesel and second-highest for petrol in the EU is a cruel and needless burden on the millions who have no option but to commute to work and shop for essentials by car.
"This is why so many complain they're spending so much of their incomes on mobility.
"A fuel-duty cut of three pence in the Budget would hugely benefit everybody in the UK, but especially the poorest."
But one Highland MP warned the cut would not solve the problems facing the most remote communities where forecourt prices are far higher than in the main towns and cities.
One website says fuel at Tarbert on Harris is 137.9p a litre for petrol and 144.9p for diesel, while both are 7p cheaper in Edinburgh.
Rob Gibson, SNP MSP for Caithness, Sutherland and Ross, said: "The cost of delivering is the important element for so many rural communities.
"What we should be trying to do is to find a way of introducing a flat-rate charge for fuel, so that it costs the same no matter where you buy it.
"That's the only way the disadvantage of rural communities can be tackled. But it is true that the high tax on fuel is a very real burden on our economy."
FairFuel UK say Mr Osborne taxes diesel more than the finance minister of any other European country. Campaigners contrasted Britain with the "powerhouse economies" in Europe, and more troubled countries, which all subsidise diesel prices through lower tax than petrol.
The UK's tax on the fuel is higher than Austria, Belgium, Croatia, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Lithuania, Latvia, Luxembourg, Malta, the Netherlands, Portugal, Slovakia, Slovenia and Spain.
The campaigners say these countries recognise that a subsidy helps businesses and the economy and question why the Treasury does not do the same for UK hauliers, "the engine room" of the economy.
FairFuel UK pointed to research by the National Institute for Economic and Social Research last year, claiming it showed a 3p cut in fuel duty would generate GDP growth of 0.2% and create 70,000 new jobs across the UK - and cut inflation further.
Howard Cox, co-founder of the campaign, said Mr Osborne had previously been receptive to their arguments, particularly with the 2015 General Election lying ahead.
He added: "A fuel-duty cut would be self-financing and a vote winner. This punitive tax on UK road users has to be slashed."
A UK Treasury spokesman said the Government had taken repeated action on fuel duty. This year's increase would be cancelled so instead of petrol taxes going up by two pence a litre, they would stay frozen.
He pointed out the Government has abolished the Labour administration's fuel-duty escalator, which meant petrol and diesel went up a penny a litre above inflation every year.
It meant petrol was now 20p cheaper than it would have been under the previous arrangements.
He said that on top of that there was the 5p a litre rebate for the Scottish islands.