They make look like thinly disguised replacements for Honda's NSX supercar and Insight electric car, but the company was refusing to admit that its concepts were any such thing at the Tokyo Motor Show.

Unofficially it's a different story with the IMAS and HSC (Honda Sports Concept) expected to go into production before too long. Most blatant was the HSC which still looks like the current NSX from the front. Designer Toshinoba Minami, however, denied that his baby was set to hit the showrooms.

"It is a design study going back to sports car origins," he said. "A lightweight vehicle with a compact, high powered engine. Normally you would expect to find a V8 or V10 engine in such a car, but we have put in a V6 3.5-litre engine which produces as much power as either of those." 300bhp, to be precise.

Insiders say the NSX replacement, which will be "pretty close" to the Tokyo concept, is due in 2006 or 2007.

The IMAS, designed by Jose Wyszogrod, bears some resemblance to the current Honda Insight environmental car and boasts ultra low aerodynamics for greater efficiency. Unlike the Insight it is a four-seater, or 2+2 rather than a two-seater.

IMAS uses a hybrid system with petrol engine and electric power sources.