The MBTA spends more money on bus maintenance than every other major transit system in the country, according to a Pioneer Institute report that dubs the work ripe for outsourcing and could reinforce the agency’s push to privatize several of its garages.

“We’re No. 1 — and it’s not good to be No. 1,” said Greg Sullivan, the former state inspector general who authored the report using federal transit data.

“The staffing at the maintenance garages, the amount of time taken per job and per bus, is tremendously higher,” he said. “As a former inspector general, one thing I’ve come to learn is putting out bids for services is a great way to save money.”

The report, which will be released today, comes as T officials prepare to release a request for proposals from private companies to take over bus maintenance in at least four of its garages.

The move has drawn swift resistance from unions representing mechanics.

According to the report, in 2015, the T spent more than $44 per hour on bus maintenance for each bus that was running — a standard used by the feds — which amounted to the highest of any of the country’s 25 largest transit agencies and 65 percent more than the average.

Sullivan said the T could save $43.7 million if it cut its bus maintenance expenses to the average of its so-called “peer agencies,” which include systems in Miami, Atlanta, Pennsylvania, Maryland and Washington, D.C.

But Mike Vartabedian, area director for the International Association of Machinists, said it’s unfair to compare the T to the warmer-weather operations, arguing that the other agencies aren’t working with the type of aging equipment and facilities as the T.

“The machinists union has approached the MBTA and told them we would be willing to sit down and see if we can provide a better break for the taxpayers,” Vartabedian said of bargaining talks. “I don’t think it’s in their agenda.”

Officials have said that outsourcing work at four of its nine garages could save $26 million annually, based on unsolicited proposals several companies provided.

“Until you have hard bids from the marketplace, you don’t know what the price is,” said Brian Shortsleeve, the T’s acting general manager, noting officials are still in the process of creating an RFP to release, a move he said doesn’t require board approval. “I would say this report is consistent with … the proposals we received.”