The illustration, which was first seen in June last year, has been released again to ascertain public response to the model.
Peter Boutwood, managing direct or Noble, said "We haven't built or tested one, but it is a feasible project."
The M600 roadster would utilise a removable roof panel, made of lightweight carbonfibre. When removed, it would be stowed in the M600's engine bay, in order to prevent it reducing the available interior or passenger space.
Removing the roof panel would have no affect on the M600's handling capabilities, as the roof panel isn't structural. Boutwood added "It's not about how it looks, it's about how it goes and drives. We would never compromise the car".
A roadster version of the M600 would be mechanically identical to the standard M600 coupé, which is powered by a 4.4-litre twin-turbo V8. Power output of the current M600 is rated at 650bhp and 604lb ft, all of which is sent to the rear wheels via a six-speed manual transmission.