Well the guy im buying the car from did some mersuering and he came up with 11 cubes and some change not sure on his math but i could use some imput from you guys.If you all know how a RX7 is shaped ,from behind the seat in the hatch area,from the shelf to roof is 21".At the rear where the hood latch is is 10"I have either 36 or 40" in depth and 36"wide all the way back.He came up with approx 11 cubes not taking thickness of mdf and double baffle and bracing,if that helps out any.