They are keenly sought-after sporting classics, both black and eye-wateringly beautiful to aficionados of their respective marques.

But while just 10 years separates their build dates, the two roadsters being offered at Shannons Melbourne summer Auction on Monday November 26 could have been built on different planets rather than in neighbouring countries.

The Porsche 356B Super 90 Roadster is unquestionably one of the best of the 1529 examples of this variant built in Stuttgart in 1960 and one of the rarest of all the 80,000-odd Porsche 356 models produced from 1948-1963.

Although a successor to the more famous 356 Speedster, which was a base-specification model originally developed for the American market, the Roadster featured much greater creature comforts and came with a proper windscreen and a weatherproof folding roof.

The example car being auctioned was also built with the optional and more powerful Super 90 1600cc engine and is correct in every detail down to its driver’s handbook and toolkit, making it is one of the most desirable of all Porsche 356 models.

Comprehensively restored and mechanically rebuilt over a two-year period during 1999 and 2000 by Melbourne Porsche specialist Peter Hardt, the 356 has been a consistent concours and People’s Choice winner since its completion and is well known to members of the Australian 356 Register.

Shannons say its guiding price range of $120,000-$150,000 is well under the money lavished on the car during its restoration.

Totally different to the Porsche in its mechanical layout, voluptuous styling and character, is the very original and unrestored black 1950 Jaguar XK120 that is also being auctioned by Shannons on Monday.

As Jaguar's first post-war sports car, the XK120 was the sensation of the 1948 London Motor Show and when chassis No 660196 was delivered new to real estate agent Colin Anderson by Brylaws of Melbourne in February 1951, it was a real traffic stopper.

As ordered by Anderson, the car was equipped numerous special features, including a detachable hardtop, special soft top, a different exhaust pipe outlet and a set of particularly desirable chromed and fluted wheels – believed to be one of just five sets made by Jaguar.

The present owners acquired the Jaguar in March 1977, by when its odometer read just 48,000. In the past 30 years this has crept up to only 53,300 miles.

Apart from its refreshed paintwork, the car remains in remarkably original condition and retains its original and very stylish colour combination of black paintwork with biscuit and red leather upholstery.

The car is being offered for sale for the first time in many decades and Shannons believe it to be one of the most original XK120s left in Australia .

It is being sold registered in Victoria with the number plates 'XK-0120'. Shannons are quoting a guiding range of $90,000-$110,000.