WASHINGTON (Reuters) - The Obama administration on Tuesday will finalize the first ever fuel efficiency and emissions standards for commercial trucks, vans and buses, which is expected to save owners $50 billion in fuel costs over four years.

The standards are expected to save the United States some 530 million barrels of oil over the same period beginning in 2014, according to senior administration officials.

"Increasing efficiency standards over the last 30 years has not been something that our country has particularly excelled at, but it has been a priority of the Obama administration to move forward with aggressive new standards," said an official in a telephone news conference.

The president will announce the standards to an audience of auto company executives, green groups and workers in Springfield, Virginia.

The announcement comes a week after President Obama declared aggressive fuel economy standards for personal cars and light trucks. The program for commercial vehicles, like last week's, is part of the administration's goal of reducing the country's dependency on foreign oil by one third by 2025.

Standards apply to vehicles divided into three categories and to all models made between 2014 and 2018. By the end of that period, long-haul trucks will be required to reduce fuel consumption and greenhouse gas emissions by 23 percent. Vocational vehicles -- delivery trucks, school buses and the like -- will reduce consumption and emissions by 9 percent.

Regulations for heavy duty pickup trucks and vans will differ for those powered by gas and those by diesel. Gas-fueled vehicles will reduce fuel use by 10 percent and carbon emissions by 12 percent. Diesel-powered trucks and vans are to reduce oil use by 15 percent and emissions by 17 percent.

Regulators shifted targets slightly in the final plan. The fuel reduction target is slightly higher for long-haul trucks and lower for vocational vehicles than was unveiled in the plan last year. The government also estimates more in oil savings.

The measure has "very aggressive support" from the heavy duty auto industry, a senior official said. Expected to attend the event on Tuesday are truck and parts manufacturers Navistar, Eaton, Daimler AG, Volvo, Chrysler (which is run by Fiat) and General Motors.

Truckers are projected to haul about 14 billion tons of freight by 2018, compared with nearly 11 billion tons in 2006, industry figures show. Commercial trucks represent about 11 percent of all registered vehicles in the United States.

Companies will get bonuses from the government for emission credits gained from using clean technology.

Administration officials say the costs to the industry are negligible. To upgrade a tractor trailer truck, for example, will cost $6,220 but will save an estimated $73,000 dollars in the lifetime of the truck.

For pickup trucks and vans the costs could be around $1,050, and for vocational vehicles just $380.

"One of the reasons there is much support ... is that people recognize that, one, these costs pay for themselves quickly," said a senior administration official.

(Editing by Russell Blinch and Jim Marshall)