Audi is celebrating the 10th anniversary of its first all-aluminium bodied car.

At the 1991 Frankfurt Motorshow, Audi amazed the motoring public with the quattro Spyder concept car .

Then a month later in Tokyo it unveiled its futur-istic sportscar in polished aluminium, the Audi Avus, and this was worldwide headline news.

Englishman Martin Smith was a member of the Audi Design team involved in the Avus project, named after a Berlin racetrack, recalling the racing heritage of the great Auto Union record-breakers of the 1930s.

The Audi Avus quattro can be viewed today in Audi's Museum in Ingolstadt.

Having co-operated with the Aluminium Company of America on the development of a lightweight production car, Audi's aim a decade ago was obvious:

n compared with an equivalent steel structure, an aluminium body could be as much as 40 per cent lighter.

n this would help reduce fuel consumption without sacrificing either comfort, convenience or performance.

n plus aluminium is an environmentally friendly material which can be reprocessed almost an unlimited amount of times without sacrificing its quality.

The world debut of the Audi all-aluminium body was the most significant automotive advance since the heavier steel monocoque was invented in the 1940s.

This itself replaced the separate body and chassis assemblies that went before it.

The key Audi advance was the use of aluminium for the entire body structure, with the use of a highly advanced space frame concept involving aluminium castings and extrusions to form the vehicle frame.

Very different from steel framed cars with occasional aluminium panels.

At the 1993 Frankfurt Motor Show, the design study entitled Audi Space Frame the forerunner of today's aluminium bodied Audi A8 was shown. The body used new structural principles whereby every panel surface contributed to a load-bearing effect.

Extruded aluminium sections were connected together by pressure-cast joint elements and large-area sheet aluminium panels integrated into the resulting cellular structure.

Improved aluminium alloys and process tech-niques from research work resulted in the Aluminium Audi celebrating its world premiere as the successor to the Audi V8 at the 1994 Geneva Motor Show.

The new model designation A8, the first production saloon with an aluminium body, also heralded a general renaming process within the Audi model programme.

Audi has now built more than 172,000 aluminium bodied vehicles.

These include almost 100,000 Audi A8s and more than 74,000 A2 models.

At the end of 1994, Audi concentrated its expertise in the field of lightweight construction at its advanced Neckarsulm plant.

Erecting an aluminium centre cost around DM 15 million which works out at £5m

Today, more than 100 development engineers and technicians work at Neckarsulm.

They are concerned in particular with optimising components and processes for volume application in ASF technology.

A workforce of more than 1,500 and 500 work on the A2 and A8 assembly lines respectively.

This development work has produced visible results the Audi A2 with the second-generation ASF which was launched last year.

This, the first volume-built aluminium car, required techniques, processes, tools and production methods to be developed from scratch or modified.

The Audi A2 1.2 TDI then eventually followed in June of this year.

This was the first five-door 3.0-litre car (one that consumes just three litres of fuel per 100 km) that makes no compromises in terms of space, comfort and driveability.

And a beauty it is.