Almost Great: Audi 100 CD

One more piston may have made the difference to this classic 1980s mid-size executive sedan from Audi. 

Automotive design is often inspired by simple needs. Henry Ford wanted a car that could be built quickly by people with no specific skills. The Citroën 2CV with its long-travel suspension was designed to cross a farmer’s ploughed field without breaking a cargo of farmyard eggs, while Alec Issigonis wanted a car that would accommodate four adults and their luggage in a structure less than 3 metres long. No one in the 65 years since it appeared has designed a more space-efficient vehicle than Issigonis’ Mini.

Audi saw a need as well. In a world obsessed with fuel efficiency there existed an irreconcilable conflict between consumer demands for spacious vehicles and smaller, more efficient engines. 

For Volkswagen’s upmarket subsidiary, the quest was to adapt its front-wheel drive 5E model to meet the needs of an executive vehicle segment that wanted its cars to be stylish and roomy but also economical.

Key to Audi’s quest was the science of Applied Aerodynamics and there, parked in the corporate museum, was a working blueprint.

The 100 CD drew inspiration from the aerodynamic principles Audi's predecessor NSU had implemented on the Ro 80 (Image: Audi AG)

More than a decade earlier, the now defunct NSU had attempted to dramatically advance passenger car design with its Ro 80 sedan. As you might guess from the designation, this sleek four-door was powered by a derivative of Dr Felix Wankel’s dual rotor engine, but it was the shape and structure of the car that would exert a lasting influence.

NSU, with minimal resources but great anticipation of future needs, used a wind tunnel to fine tune the Ro 80 shape. Because the engine was relatively tiny, displacing just 994cc and producing 85kW, the shape of the car needed to slip efficiently through the air and deliver a target drag coefficient of just 0.35.

Late in the 1970s when Audi dusted off NSU’s drawings and wind tunnel results, it found inspiration in a car with smoothly curving body panels, a sloped nose, tall tail, flush glass and pillars that were virtually invisible.

Audi claimed that its original prototype for the 100 CD, without disruptive items like wipers and mirrors, managed a drag coefficient of 0.25. In production form, the design achieved a still impressive 0.30, with alloy wheels instead of the standard flat hubcaps making minimal difference.

Audi claimed that its concept vehicles without items such as wing mirrors achieved a 0.25 cD, while the production version still managed an impressive 0.30 cD (Image: Audi AG)

Some observers believed that the CD suffix was intended to celebrate the car’s defiance of wind resistance and were disappointed when informed that the letters stood for Corps Diplomatique (Diplomatic Corps), based on a belief within Audi that many of the cars would undertake Ambassadorial duties in countries worldwide.

The new version of the 100 certainly had space in the back to accommodate a portly Charge d’Affaires, with driver and minder occupying the buckets up front. Shoulder, leg and headroom were all improvements on the 5E version being replaced, but mechanically the car hadn’t moved with the times.

The quirky engine still displaced just 2144cc, with five inline cylinders, a single overhead camshaft and fuel injection. As installed in German-spec CDs, the 2.2 produced 100kW and although later years would bring a 200T turbo version. Here in Australia, we saw only the basic motor until 1986. 

Cars certified for Australia also lost a little power due to our poor-quality fuel and were rated at 96kW. Most came with three-speed automatic transmission, however the version to get if you could find one was the five-speed manual.

Despite not being the most powerful car in its class, few bothered to calculate its impressive power-to-weight ratio (Image: Audi AG)

Weight of just 1210kg provided an advantage over heavier rivals like the 230E Mercedes-Benz, while its exceptional coefficient of drag helped the 100 CD maintain a steady 180km/h in places – such as German autobahns – where such speeds were allowed.

Most buyers when considering the 100 CD didn’t bother working out its impressive power-to-weight ratio, they just looked at a little engine with an odd number of cylinders enveloped by a car of substantial size and went looking for something else.

Early 100 CD models supplied to Australia were further hampered by ‘autobahn gearing’ which with 45km/h per 1000rpm saw them turn at 2400rpm at 100km/h on the freeway, but take 15.7 seconds to reach 100km/h from rest. Yes, this expensive German saloon was slower than your Aunt Christine’s Corolla.

By late 1985 in response to Australia’s shift to 91 RON unleaded fuel Audi introduced a more powerful 101kW version of the 100 CD with a revised final drive ratio. Acceleration times improved noticeably, with the 0-100km/h sprint reduced to a gazelle-like taking 12.7 seconds, and the range expanded with the introduction of a world-class station wagons.

The Avant with its sloping rear window echoed the sleek profile of the sedan while offering an immense load area and an extra hidden feature. Because Avants supplied to Australia had only five seats and cars in other markets could seat seven, we got a deep and large sub boot where valuables could be stored out of sight. 

The Avant model had a distinctive sloping rear window atop its immense boot, but buyers failed to be drawn in by it being longer and lighter than the equivalent Merc wagon of the time (Image: Audi AG)

Despite being 60mm longer than a Mercedes-Benz 300TE wagon, the automatic Avant at 1380kg was 240kg lighter; an advantage that, in common with the sedan, seemingly didn’t register with potential owners.

Concerns about balancing an engine with an uneven number of cylinders created angst as well, especially amongst potential buyers whose alternatives included the six-cylinder, 3.0-litre Mercedes-Benz or 2.8-litre BMW. Not even the promise of significant fuel savings and  performance to match the compact Benz seemed to help.

Last gasp for the CD Series in this country came during 1986 when the first of two shipments (12 cars in each) of turbocharged 200T sedans arrived. The first batch, imported by outgoing distributor LNC Industries, ranked amongst the most overpriced vehicles ever offered to the Australian market with a listed cost of $92,594. A V8-engined Mercedes-Benz 380SE was $5000 less.

Sales were predictably slow, with one car allocated to press testing, one to the LNC CEO and the rest acquired wholesale by dealer principals with Audi/VW sales outlets. Even so, those same dealers would tear up thousands in write-downs when the price of the second batch of 12, brought in by newly appointed distributor Ateco Industries, dropped to $76,000.

There are almost no remaining examples of the 100/200 CD left in Australia, although they are more populous in the left-hand drive US market (Image: Audi AG)

In overseas markets, the 200T could be specified with Audi’s marvellous Quattro all-wheel drive system and five-speed manual transmission. In the USA, where more than 40,000 full-sized Audis sold during 1986, the Quattro Turbo with manual transmission ran 0-60mph (0-97km/h) in 8.3 seconds, had a top speed of 212km/h and would average 8.5L/100km. 

Survivors from the 100/200 CD era are almost extinct in Australia today, and cars that do exist will typically be uneconomic to restore. Sourcing one from the USA and registering it left-hand drive is possible and would not be particularly expensive – if you can find a car to buy.

At the time of writing, US market monitoring site Classic.com had spotted a 5000CS Quattro manual sedan in what was described as ‘highly original’ condition and showing 109,000 miles (175,500 km) which sold at auction for US$7900 or around A$12,000.

Rust shouldn’t be too much of an issue with local or Northern Hemisphere Audis because from 1986 the body structure and panels were made using galvanised steel. 

Valuation Timeline: Audi 100 CD