Porsche has released details and pictures of its lightest Boxster yet - the new Porsche Boxster Spyder.

Weighing in at 1,275kg, the mid-engined Spyder joins the standard Boxster and Boxster S while boasting a folding soft-top.

The lightweight chassis, lower centre of gravity and revised suspension enables the Porsche Boxster Spyder to go from 0-62mph in 4.8 seconds and on to a top speed of 166mph.

The re-tuned 3.4-litre engine puts out 10bhp more than the Boxster S. The Spyder also weighs 80kg less than its hard-top brother.

Porsche says it's this formula which made previous models so successful, including the 550 Spyder from 1953 - which weighed just 550kg - and the modern RS Spyder Le Mans Prototype race car.

To put its lightness into comparison, a Lotus Elise weighs between 710-903kg, a Mazda MX-5 is 1,150kg and a Lamborghini Gallardo Spyder weighs 1,520kg.

Not to confuse the new Boxster Spyder with a series of special editions built in 2004 and 2008 bearing the same name, Porsche says the new model is a "specially developed and upgraded production model with far-reaching modifications versus the Boxster and Boxster S."

An optional twin-clutch PDK transmission brings the average fuel economy up to 30.4mpg. Expect the manual gearbox model to have a fuel economy of around 29mpg.

Other changes include extra-low side windows and two bulges on the rear lid, creating a look more reminiscent of the Carrera GT.

Buyers will also receive an invitation to the Porsche driving experience at Silverstone to "develop their own skills behind the wheel."

The new Porsche Boxster Spyder will debut at the LA Auto Show on December 4.

It will arrive in the UK in February 2010 with prices starting at £44,643.

Gallery: more images of the Porsche Boxster