Audi Dual Mode 3-Cylinder Power - First Drive By Henny Hemmes

Audi develops 3-cylinder engine and Henny drives the prototype A1-e-tron dual mode hybrid

By Henny Hemmes
Senior European Editor
The Auto Channel

ISMANING, Germany, October 15, 2012; Recently, Audi presented its newly developed 3-cylinder TFSI petrol engine during its ‘Innovation Day’. The 1.5-liter engine made its unofficial debut as a range extender in a prototype of the A1 e-tron with the so-called dual-mode hybrid power train. It replaced the small 254 cc rotary engine that has been used so far in the A1 e-tron, of which some 20 units ran a test program with customers during 14 months in Munich. The test ended in September and provided a view on customer usage, charging and vehicle performance. The most important conclusion was that the drivers, after getting familiar with the system, used the A1 e-tron in practically the same way as they had done with the A1 with the 1.4 TFSI engine. In the course of the test program, the drivers increased driving in electric mode from 76 to 91 per cent. Next year Audi will continue its testing program by means of participating in the ‘Electromobility Showcase’, promoted by the Federal Ministry of Education and Research.

Dual-Mode Hybrids

At the Paris auto show, the Germans presented the Crosslane Coupe concept with the dual-mode hybrid system, which uses the same technology as VW’s TwinDrive system. The dual-mode system includes a small and a larger electric engine and one petrol engine, in this case the 3-cylinder unit.

Unlike BMW, Audi AG did not develop a complete new motor, not did it look in the parts bin of Volkswagen, that builds a 3-cylinder for its micro car, the Up. Derived from the 2.0-liter 4-cylinder TFSI engine (one cylinder has been ‘cut off’) , it produces 95 kW/130 hp and has 148 lb-ft or torque.

The 3-cylinder is connected to a disc shaped electric motor (50 kW/68 hp and 155 lb-ft of torque), or EM1, that mainly functions as starter and generator. The second electric motor (85 kW/116 hp and 184 lb-ft of torque), the EM2, handles the electric traction. A single-speed gearbox manages the mechanical connection between the engine/generator and the rest of the driveline through a claw clutch. The 17.4 kWh battery is placed mostly beneath the rear seats and delivers an electric range of some 55 miles. Audi claims an average fuel consumption of approximately 1 liter per 100 km, or 235 mpg, with 23 grams CO2.

The advantage of the Dual-Mode concept is that offers different operating modes. In the so-called urban mode, acceleration up to 34 mph is handled by the main electric motor. When the battery does not have sufficient energy, the system switches temporarily to series operation and the EM1 provides electrical energy. In serial mode, the IC engine is at work and the generator motor is the back up.

Room for refinement

When I step into the cockpit of the A1, the engineer joining me once again says “this is a pre-development prototype.” That makes you realize that Audi is not finished yet with the development of this new driveline. It is also an excuse for the typical 3-cylinder sound, which should be easily resolved by applying sound dampening. It also indicates that Audi knows it has to work to make the engine running in a more refined way and may be use an internal balance shaft, just like BMW does with its 3-cylinder?

Anyway, we hit the road and of course, also wanted to know about acceleration. The chronograph on my wrist showed just over 9 seconds for zero to 62 mph in electric mode and just under 9 seconds in dual mode, but it feels quicker.

Over 34 mph, you do not notice the 3-cylinder engine to be ‘engaged’, but you’ll hear its sound when you really push it. The system works really smooth when we drove through the villages around Munich.

I should not forget to mention that you can chose an ECO or SPORT setting and when you drive in the city, you can also choose electric mode with a push on the EV button.

When a colleague asked if this new 3-cylinder engine has been specifically developed for the dual-mode hybrid, Audi would not confirm that. But given the fact that Ford already offers its Focus with a 3-cylinder motor and BMW is going to do so from 2014, you may bet that Audi has plans as well. But it will take probably a couple of years, before we may see it in a production model.

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