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The e-tron® isn’t our first EV. Let’s look back on the Audi Duo.
The story of the Audi Duo provides a classic example of an idea ahead of its time.
When most of us think of hybrid cars, we think of the Toyota Prius, originally released in Japan in 1997. But Audi offered one at the Frankfurt Motor Show in 1989, the Audi Duo 100 Avant, a pioneering vehicle that influenced hybrids for decades to come.
Forward-looking features
By the time the Audi Duo, based on the Audi 100 Avant quattro, premiered in Frankfurt, the concept had undergone several years of intensive research and development. Its engineers noticed a number of emerging problems in auto engineering, many of which hadn’t been noticed by other manufacturers at the time and may not have been addressed until years later.
“The Duo could drive emission-free in the city and with a combustion engine between cities.” 
—Marius Lehna, leading engineer on the Duo III
A key insight that our engineers recognized was that the traditional all-wheel-drive system—set up for an internal combustion engine—was inefficient at low speeds and placed excessive stress on the rear axle. They circumvented this problem by using a five-cylinder combustion engine to drive the front wheels, and a part-time 9.3 kW electric motor, driven by a nickel-cadmium battery, for the rear wheels. This is the configuration used in many modern hybrids.
The solution was for the Audi Duo to automatically switch to electric power at lower speeds, helping the car run more efficiently overall. Since they included both motors, the Audi engineers added a system that enabled drivers to switch between gas and electric motors. In short, they created a full-featured hybrid vehicle in 1989, helping set the stage for today’s hybrid vehicles.
A challenging debut
But like any innovation that is breaking barriers, there were some limitations. The engineers said the car could go 0–20 mph in eight seconds, which was a challenge for a performance brand. Plus, the Audi Duo weighed 440-plus pounds more than an equivalent gas-powered model—which limited its gas mileage potential.
Even so, when the Audi Duo premiered in Frankfurt, audiences were intrigued by its original concept. The Four Ring manufacturing department recognized enough public interest to continue the research and development, resulting in the Audi Duo II.
A succession of innovations
Ingolstadt unveiled the Audi Duo II concept, based on the Avant quattro, in 1991. It featured a more modern 2.0-liter engine and a larger, 21 kW electric motor feeding power to the all-wheel-drive system. The more advanced electric motor and battery system could decouple the front axle and directly drive the rear wheels. Thanks to the updated design and technology, the driving range increased to about 49 miles.
Six years later, Audi premiered a limited-edition plug-in hybrid in Europe: Audi Duo III. Based on the next-generation A4 Avant, we installed a pressure combustion engine to account for the extra weight of the EV components. In a break from the previous-generation Duos, the engineers abandoned the quattro® all-wheel-drive system. The Audi Duo III plug-in would drive only the front wheels. Regenerative braking was added to recapture energy on deceleration and downhill driving—technology found on most hybrids today.
The Audi Duo III was the first European hybrid vehicle to be put into production, and it was limited to 60 vehicles that were leased to consumers.
Throughout the 1990s, Audi unveiled one inventive hybrid after another, anticipating modern designs and features by years or even decades. Very expensive cutting-edge technology—on top of an already expensive vehicle—combined with a changed political landscape to make mass production a challenge. We never gave up on the perfecting the technology—and when we rolled out the Audi Q5 hybrid quattro in 2011, consumers were ready.
"Between the Duo I and the Duo III, the efficiency “from battery to wheel increased significantly.”
—Marius Lehna, leading engineer on the Duo III
Today, it’s easy to see that the Audi Duo series would have been more at home in 2009 than in 1989. That series shows how our engineers were creating the future decades ago.
For a glimpse of what the automotive world will look like in 2030 and beyond, just look at what we are working on today. If the Audi Duo is any indication, innovation today is creating the vehicle of tomorrow.
The story of the Audi Duo provides a classic example of an idea ahead of its time.