MotoringFile says that,
[D]ue to MINI increasing rigidity with extra bracing (where the rear seat would be), additional pedestrian impact safety, the rear movable spoiler and several options that are now standard on the R58, the Coupe is actually around 45 lbs heavier than the hatch.
However, reports also indicate
the R58 is not only faster than the R56 hatch in a straight line but also around any track thanks to better weight distribution and better aerodynamics.
You can also expect weight creep in the hatchback as MINI integrates the additional pedestrian impact safety into the next generation of the vehicle.
