What dimension though? Because I bet if you wrapped both the Brompton and the Carryme in watertight plastic and submerged them in water the Carryme would probably displace less than 2 cu in of water while the Brompton would probably displace close to 4.5 cu in; Reason being that the 10.5" width of the Carryme comes almost entirely from just the pedals and, moreover, the cross section is overall much more triangular than rectangular whereas the Brompton is pretty much a rectangle.

Now I have no idea why anyone would be interested in this volume, but neither do I know why anyone would be interested in the volume of the rectangular box of smallest volume enclosing the bike (as computed above in the LxWxH calculations of Bacciagalupe) apart from sending the bike somewhere via Fedex.

The dimensional quantities I am interested are:
-The area of the 2D projection of smallest area (ie the footprint)
-The volume of the portion of the rectangular box which minimally exceeds the standard crotch/foot region.
-The sum of linear dimensions exceeding airline carryon specification.

But I'm not interested in the volume of the the rectangular box of smallest volume enclosing the bike because there really isn't any aspect of my life which restricts that particular quantity.