Mercedes-Benz SL official images leaked

And the images show that the world's oldest car has been back to the beauty parlour for a major makeover to continue its run deep into the 21st century.

Mercedes-Benz claims the ancient crown for its SL roadster, which hit the road in the 1950s and has continued along the same path for near-enough to 60 years.

But the latest makeover, which will be previewed at Detroit motor show in January and available in Australian showrooms by June, is more than just skin deep.

The sixth-generation is the first Mercedes-Benz to be constructed almost entirely from aluminium - there is steel strengthening and magnesium in some places - and it also comes with two developments which are claimed as world firsts.

The car has a FrontBass system that Benz claims will turn it into a concert hall with the top up or down, as well as an adaptive windscreen cleaning system called Magic Vision Control.

But the SL is really about luxury and style, despite a $242,780 starting price that means only 23 have been sold through the first 11 months of 2011, down from 48 at the same time last year. Despite the small numbers, Benz says the SL is a landmark car for the brand.

"It is a flag bearer for us," says David McCarthy, spokesman for Mercedes-Benz Australia. "It's a pretty good indicator of where we're going. It continues the design theme of the SLS and SLK."

He is also keen to highlight the longevity of the SL badge, which was first applied to a Benz in 1952 and reached Australia a year later. 

"In passenger cars, it is the longest-running nameplate in the world. The only one that comes close is the Chevrolet Suburban, which has a longer history but is an SUV," McCarthy says. "The only other one that came close was the Ford Fairlane, which only lived on in Australia until the 21st century until they chopped it."

McCarthy confirms the usual model spread for the upcoming SL, which currently runs from the SL350 to the SL 65 AMG at $519,250, and a sharp bottom line.

"We don't expect a big change, price-wise. It will be on sale in the second quarter in 2012 at the earliest for us," he says.

On the specification front, apart from the latest technology and a body that is both lighter are larger in most directions, the SL comes with engines that have more power but economy improved by as much as 29 per cent.

"There is the new V6, then the V8s and the AMG models. The 350 is currently the biggest seller and we expect that to continue."

The car's folding hardtop vario-roof operates in either direction in less than 20 seconds using an electrohydraulic mechanism, and will be available with a painted finish, a glass roof or the Magic Sky system - first fitted on the SLK - which switches from light to dark inside at the touch of a button.