Porsche will expand its model lines to four with the introduction of a new Boxster-based sports car for the 2006 model year.

Positioned and priced between the Boxster S and 911 Carrera, the new two-seater, named the Cayman S, is said to be aggressively styled to reflect its enhanced handling and more powerful engine. At the same time, highly efficient space utilisation makes it one of the most practical sports cars in its class, the automaker said on Thursday.

The new model has already been 'scooped' by magazine spy photographers though most pundits thought the disguised prototypes caught so far were for a new closed coupe version of the Boxter, rather than a separate model line.

Porsche has now confirmed the Cayman will be a fixed-roof model rather than a convertible with optional clip-on hardtop, like the Boxter.

The automaker said the Cayman S derives its name from the smallest of crocodiles, the caiman, which is known to be swift and nimble. It will have a mid-mounted 295 bhp (217kW), 3.4-litre, six-cylinder 'boxer' engine.