Though, with a little stretch of imagination, Sucahyo's hybrid-findings could make it possible to mate the drivetrain of the original Mini Cooper, which is found in the guts of the ugly Mini Marcos, with the body of the new BMiniW... But, I'll go take a look at the body-charts Sucahyo created - might find something there.
EDIT: And I'm back with an answer:
Looking at the charts, there's only one mention of an original Mini - the name-code. When used in PHASTE (which is the way to create hybrids) on any car, the name of that car will change to "Mini Cooper 1.3l". However, not all is golden - the manufacturer isn't set, so pressing "R1" to call up the origin-country on the main GT-Mode screen makes PCSx2 crash - I reckon the actual game will lock up then. So technically, you could create an almost-proper Mini, with only the body and engine missing - the guts can be borrowed from the Mini Marcos, and only then engine will have to find a replacement. Body could be the one from the new BMiniW...
I searched, but couldn't find engine, drivetrain, chassis, body, or any other mention of the original Mini. Perhaps Sucahyo left something out in his lists, but I doubt that.