Audi Typ A (1910)
Audi was founded by August Horch who left the Horch company in 1909 after 10 years in charge. The name Audi is a rather laboured pun on the word Horch, which means "listen" in German, while "Audi" means the same in Latin. The Typ A was a 2.6 litre model positioned in the upper-middle part of the market - not so different from the current A4 in fact.
Auto Union Silver Arrows (1934 - 1939)
In the 1930s, the Auto Union racing cars were terrifyingly fast. Quite capable of 300 km/h (186 mph) with skinny tyres and rudimentary swing-axle rear suspension (later described by Ralph Nader as an unsafe design for a 34 bhp VW Beetle), it was hard to know if they were more scary to their opponents or their drivers. The power output, which peaked at 550 bhp in 1938 was not equalled in Formula One until the 1980s.
DKW F89/F91 (1950 - 1955)
After the Second World War, Auto Union's factories were in East Germany and were expropriated as war reparations by the Soviets. The management of the company moved to Bavaria and set up in Ingolstadt where the company remains to this day. The first post-war model was the two cylinder, two-stroke DKW F89. When DKW expanded it to a three-cylinder design (the F91), it advertised the engine as 3=6 on the grounds that a three cylinder engine with two power strokes for every four revolutions was equal to a conventional six cylinder engine with one power stroke for every four revolutions.
German Federal Archive
Audi 72 F103 (1965 - 1972)
Auto Union had been taken over by Mercedes-Benz in 1958, who set about designing a new four-stroke engine for the DKW F102. Before the engine was ready, Mercedes sold Auto Union to VW (how much must they have to come to regret that sale?), but the re-engined DKW was ready for 1965. VW thought DKW was a name associated with smelly two-stroke engines, so called the revised car the Auto Union Audi instead. Thus to begin with Audi was just a model name. The name Audi 72 came a year or so later when Audi was upgraded to manufacturer status.
Audi 100 C1 (1968 - 1976)
This rather bland looking saloon is probably the most important Audi of all. VW had decreed after the takeover that Audi would design no more new cars and just become a VW production facility. Audi told VW they were simply facelifting the 72. By the time the truth came out that it was an all-new car, VW was so impressed that it agreed to put the Audi 100 into production and keep Audi as design centre.
NSU Ro80 (1968 - 1977)
NSU was an independent company that bet its future on the amazing Ro80 - and lost. The Ro80 featured a Wankel rotary engine, a new semi-automatic transmission and a radical bodyshell. Warranty claims for the rotary engine bankrupted NSU and it merged with Audi - and some of its ideas were to reappear in Audis 15 years later…
Audi 100 Coupe C1 (1970 - 1975)
Audi wanted to jazz up its staid image with a stylish coupe. The resulting 100 Coupe was just the job - it looked more expensive than it was, with hints of the contemporary Aston Martin DBS in its shape. As Audi's job in the seventies was to make upmarket VW saloons, the 100 Coupe was dropped, but not entirely forgotten. The recent design renaissance of Audi with the TT and R8 can be traced back to this lonely pioneer.
Audi 80 B1 (1972 - 1978)
At this time the VW Beetle was starting to age and VW suddenly realised it was not going to last forever. This was VW's worst period and it was even overtaken by Opel in the German market. However, part of the answer to VW's problems was to be found at Audi: its new 80 (replacement for the Audi 72) became the basis for the VW Passat. Effectively the first Passat was just a hatchback Audi 80.
Audi Quattro (1980 - 1991)
A classic symbol of the 1980s, hence its use in the TV Series Ashes to Ashes (incidentally if you were wondering how they made a Quattro slide its tail on TV, they disconnected its front driveshafts to turn it into a rear-drive car). The Quattro was yet another example of a happy accident in Audi's complex history: some smart engineers wondered what would happen if they combined the four-wheel drive system from the VW Iltis military vehicle with a passenger car chassis. The rest is history.
Audi 100 C3 (1983 - 1991)
This was the third generation 100, but the first one to turn heads. Its "aero" design became the benchmark for the whole industry with its then-unique drag co-efficient of 0.30. However, it did not come completely out of nowhere. Its designer had also been responsible for the revolutionary 1968 NSU Ro80 (see above), a car to which the Audi 100 bore more than a passing resemblance.