Details are still under wraps, but later this summer — date to be determined — MBTA passengers will get a chance to tour a mock-up of the new-and-improved Red Line trains set to hit the tracks in the coming years.

On Monday morning, Luis Manuel Ramírez, chief executive and general manager of the transit agency, tweeted pictures of a model of one of the vehicles, covered by a white tarp, as it was leaving a factory in Changchun, China.

Ramírez promised that riders would be able to get a feel for what to expect from the new trains soon enough, though he stopped short of giving away too much.

“BREAKING: The mock-up of a new #MBTA #RedLine car has left the @CRRC_global plant in Changchun, China,’’ he said on Twitter. “This summer, we’ll put it on display for the public to get a look. Stay tuned for details!’’

Officials said the mock-up will be roughly two-thirds the size of the actual train cars.

One person offered a tongue-in-cheek response to the news.

“Most people wouldn’t consider a single train prototype at a factory in rural China to be ‘breaking news,’ ’’ the person said on Twitter. “But this *is* the @MBTA, so I guess any shred of good news needs to be heralded above the constant delays/service failures.’’

The MBTA has plans to replace its entire fleet of Red Line trains by 2023.

In 2014, the China Railway Rolling Stock Corp. won a bid to build 132 Red Line cars. Then, in December 2016, the T’s fiscal control board voted to authorize as much as $277 million to buy an additional 134 Red Line cars from the company. The first cars will be delivered next year before they undergo testing.

The company, which has a plant in Springfield, is also slated to build 152 Orange Line cars.

According to T officials, the first four pilot cars are undergoing testing on the MBTA’s Orange Line “Test Track.’’

Steve Annear can be reached at steve.annear@globe.com. Follow him on Twitter @steveannear.