The Automobile Association and the trucking industry are calling on the Government to scrap road user charges on diesel cars and instead include the tax in the pump price.
Their call comes as an independent panel on the road user charges system is due to report its findings to Transport Minister Steven Joyce by the end of next week.
The review was prompted by a strike in 2008, when thousands of truckies took to the streets in protest at an unexpected rise in road user charges.
The charges vary depending on the mileage travelled and a vehicle's weight.
But critics say the system does not reflect the modern car fleet and is expensive and bureaucratic.
The Automobile Association and the Road Transport Forum want the charges included in the pump price, with heavier vehicles paying an additional tax.
Federated Farmers opposes a diesel tax, fearing it will penalise farmers who conduct most of their travel off road.
