Buy an S1 Roadster, lighter faster & better on fuel.
Better on fuel .... certainly (Ford V6 is a modern DOHC unit)
Lighter ......... yes , but not that much
Faster .... I would dispute that
But the main problem for the Roadster for me is the low ground clearance , SE London is infested with speed bumps of all shapes and sizes. I go over them gingerly in the +8 , but the Roadster (even with the modified sump from Mulberry or SiFab) is a whole lot worse.