Subway cars will be even dirtier and more crowded — plus hotter in the summer and colder in the winter — thanks to severe cost-cutting measures proposed by the city’s transit agency Monday.

New York City Transit president Andy Byford outlined the budget-saving moves at a special finance committee hearing before the MTA board, which must formally approve the plan but almost always does.

Highlighting one of the many issues already plaguing the system, the meeting, which was scheduled to start at 10 a.m., kicked off 15 minutes late — because board member Larry Schwartz got stuck on a delayed train, he told the board and audience.

“It’s the truth,” he said.

The proposed cost-cutting measures include the agency being more stingy about how much heat and air conditioning it pumps into trains, offering less service on some subway and bus lines, which will lead to overcrowding, and only cleaning some subway cars at one end of the line instead of at both.

Byford said it pains him to make the changes.

“I don’t want to do any of these things,” he said.

The move to cut the cleaning on trains comes just two months after Byford hired more than two dozen managers to help increase the tidiness of stations and trains.

“I’m between a rock and a hard place,” Byford said.

The agency could save $30 million on buses and $10 million on subways with the belt-tightening, he said.

In terms of cutting back on some trains and buses, the cost savings “are achieved by tightening the service guidelines,” Byford said. “With a little more crowding, we still won’t breach the crowding level, but we can get a little closer.”

Byford said he considered many other cuts and opted for the ones that would be “least impactful on customers.”

Board member Charles Moerdler slammed Byford’s proposals, saying there were other ways to save money, including having more cops patrol the subways and buses to prevent fare-beating.

“Service reduction is a self-fulfilling prophecy for sure. We’ve seen time and again, as you reduce buses and you give worse service, you’re going to have a greater problem,” Moerdler said. “None of this should be done. None of it.”