Porsches are special. In the last century there have been plenty of desirable cars and a host of well-designed ones. But any one of those three designs - the VW of Ferdinand Porsche, the 356 of his son "Ferry", who died last week, and the 911 of his grandson, "Butzi" - would alone guarantee the fame of the family. Add in the 917 Le Mans winner of Ferdinand Porsche's other grandson, Ferdinand Piech, now head of VW, and you have an extraordinary tale of innovation in automotive design.
So Porsche enthusiasts will of course flock to the Design Museum, where a collection of the cars of these four stellar talents are on display from Thursday. Those of us who have at one time or another owned them (years ago I had a 356B convertible and then a 912 Targa) will understand the elegance and simplicity of the designs.
But there is a second level of interest which ought to appeal to people who are not particularly interested in cars or those who are but argue that the classic Porsche concept of an air-cooled, rear-engine design has proved a blind alley. After all, 99 per cent of the world car production has water-cooled engines at the front. For this is not just an exhibition about cars; it is in a way also a history of this extraordinary century. You see the emotions and attitudes of the different years of the century embodied into its dominant consumer product.
The beginning of the century saw a great burst of innovation with two technologies, the car and the plane, being developed within 15 years of each other. Start with the oldest car, a 1900 Lohner-Porsche electric Phaeton, designed by Ferdinand when he was just 25 and built in the Lohner carriage works in Vienna.
It has two electric motors built into the front wheel hubs, and battery under the seats. Three things make this remarkable. First, this patented design was used on the moon buggy 72 years later. Second, a version of this car had four motors, making it the first four-wheel-drive car in the world. And third, because the batteries needed frequent recharging, another version of the car was designed to carry an auxiliary petrol motor to charge them - exactly the same hybrid concept that is being developed for the next generation of the Swatch car.
There is then a hiatus, for the next vehicle on display is the lightweight Sascha racing car of 1922. During the intervening period, Ferdinand served as the driver of Archduke Franz Ferdinand, heir to the Austrian throne, designing cars for Austro-Daimler, and during the First World War, the Landwehr train (again with electric wheel hub motors).
We next catch a feel for the frenetic inter-war period, with elegant light-weight designs like the little Sascha, interposed with hairy monsters like the Mercedes Monza of 1924. The car on show won the German Grand Prix in 1926. Porsche also designed the mid-engined V16 Auto Unions which challenged Mercedes in the 1930s, and which is shown in model form.
If one car links the catastrophe of Hitler and the renaissance of the German motor industry it is the people's car, the Volkswagen. The car on show, one of only two prototypes which has survived, is the black convertible presented to Hitler on his birthday in 1939, and used by him during the war. It is extraordinary not just for its historical association - the seats which cushioned Hitler's bottom - but for its modernity. The Austin 10 used during the war by Churchill and sold a few weeks ago is a 1930s antique. Five minutes after leaving the exhibition I saw a P-reg convertible VW 1302 (also in black as it happened) driving down Jamaica Road: a brand new vehicle that was virtually identical to Hitler's car built 60 years earlier.
If the pre-1945 cars catch the turmoil of the first half of this century, the post-war ones trace the recovery and rebuilding of Europe. The early cars show the make-do-and mend spirit of the 1940s and 1950s, the later ones the exuberance of the 1960s, the go-getting aggression of the 1980s and the new "designer culture" of the 1990s.
There is the little Cisitalia Grand Prix car of 1947, one of only two built, designed by Ferry Porsche. The fee from this venture Ferry used to pay the ransom for his father, Ferdinand, who had been arrested by the French on a dubious charge of murder. There is a very early 356, with its trade-mark Rubenesque flanks beaten out of aluminium rather than steel. The company switched the 356 to steel bodies when production was moved from Austria back to Stuttgart in 1950. There is another elegant lightweight, the Spyder of 1956, basically built for racing, which acquired cult status when actor James Dean crashed and died in one on the way to a race in California. As a visual reference, with its chubby sides and fat single exhaust pipe, the Spyder is a template for the latest Boxter, though the structure and mechanics are completely different.
To represent the 1960s there is naturally an early 911, but there is also a rare 8 cylinder version of the 914, the mid-engined VW-Porsche hybrid, given to Ferry by the workforce. The 914 is in a way more interesting , for the collaboration with VW was the result of Ferry's desire to keep Porsches affordable: not to be pushed into the corner of just making toys for the very rich.
The 1970s are represented by the 917, winner of Le Mans in 1970 (and six other championship races that year), with its flat-12 4.5-litre engine; the 1980s by the extraordinary 959, which looks like a 911 on steroids and has either a 450 bhp or (like this one) a 555 bhp engine. If you want one vehicle which encapsulates 1980s excess, I guess this is it.
And finally to two new products, tailored to catch two groups of buyers, those who want to look stylish and those who want to proclaim they are rich. The Boxter - cute, clever, reasonably affordable and a great commercial success story - has caught the imagination of the image-conscious 1990s and satisfies the first group. The new 911, which is styled to look like the old version but actually is a completely new design with a water-cooled engine, satisfies the second. It shouts money; affordable it is not.
The tension between ludicrously powerful super-cars and elegant lightweight solutions to human mobility will doubtless continue through the next century. Aside from Hitler's VW, for me the most interesting of all the cars was the very first: the 1900 version of the moon buggy. Could this "first Porsche" become a more relevant model for the cars of the next century - simple, effective, silent, non-polluting, potentially cheap - than it has been for the cars of this one? I wonder.
Ferdinand Porsche - Design Dynasty 1900-1998, runs from 9 April to 31 August at the Design Museum, Shad Thames, London SE1 2YD. Tel: 0171 378 6055