The roof of a Park Square parking garage could soon give way to a skyline-altering tower.

Los Angeles-based CIM Group and Boston Global Investors are partnering on a proposal to transform the eight-story Motor Mart garage into a 310-foot residential tower. The partners filed plans with the Boston Planning & Development Agency Monday and provided the first images of the project, which would reduce parking at the garage from 1,037 spaces to 672. The western side of the garage would give way to 84 residential units.

Including the 20-story tower built over the garage, the project is expected to have 306 residential units ranging from studios to three-bedroom units. The proposed project is larger than the 17-story, 280-unit design described in the initial plans CIM Group filed with the city in March.

The latest filing reveals the development team also plans to renovate the current ground-floor retail space and improve the basement to accommodate room for further retail, like a market, in the future. CIM Group, which bought the garage in 2016 for $162.5M, is part of a wave of developers redeveloping parking garages across the city for more residential use.

Boston Properties has plans for its nearly 1.4M SF Back Bay/South End Gateway Project around a parking garage at Back Bay Station. HYM Investment Group is underway with the 45-story residential component of Bulfinch Crossing, a 2.9M SF mixed-use project the developer is pursuing around the Government Center Garage.