Honda has confirmed that it has started work on a convertible version of the new NSX hybrid, due to be launched at least two years after the coupe makes its debut in 2015.

"We are looking at the convertible," said Principal Designer Jun Goto, "but we have a long way to go with it," before saying it was not yet decided even whether the roof would be a hard or a soft top.

It is however believed to be a proper roadster, and not a return to the rather unsatisfactory targa panels used on the original open NSX.

As for the coupe, Goto says that while the production car is actually completely different to the concept, you will scarcely be able to tell the difference between the two.

"The production car is larger in every direction than the concept but it looks almost exactly the same. At least 95 per cent of the exterior styling will be carried over to the production car."

Not so the interior. Unlike most concept cars whose interiors tend only to flatter to deceive often leading to disappointment when the real car is revealed, the cabin in the Honda NSX concept is actually rather more conservative than that planned for production.

Interior designer Yuki Inamori said: "We want to offer the customer something even more exciting than what you see here."

The timing of the unveiling of the production NSX has yet to be finalised but Honda is trying to get it ready in time to show at the Detroit motor show in January 2015, little more than a year from now.

It has also recently been announced that the new NSX will feature a twin-turbocharged V6 engine, all-wheel drive and a three-motor hybrid system.

Read more 2013 Tokyo motor show news.