First drive review: Audi A1 e-tron dual-mode hybrid

Audi's prototype 'dual-mode' hybrid system impresses with its simplicity and refinement

Audi A1 e-tron prototype showcases new dual-mode hybrid system

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by Hilton Holloway

21 September 2012

What is it?

This is Audi's second A1 e-tron concept, combining the best of both the range-extending principle and conventional plug-in hybrids.
Audi showed its first e-tron concept in 2010. The range-extender, prototypes of which have so far racked up 31,000 miles in the Munich area, featured a small battery pack (with a 30-mile range) with the front wheels driven by a 75kW electric motor. It was backed up by a tiny, 254cc Wankel rotary engine/generator under the boot floor which generated 15kW and added 120 miles to the range.
This, the second A1 e-tron proposal, combines the best of the Chevy Volt-style range-extending principle with conventional Prius-type plug-in hybrids.
Described as a ‘dual-mode’ hybrid, the transmission uses a brand new 1.5-litre, three-cylinder, engine which develops 128bhp and 147lb ft. This engine is combined with a 67bhp/155lb ft electric motor which, Audi says, acts mostly as a starter and alternator but can assist the petrol engine.
The second electric motor - mounted on the opposite side of the transmission from the petrol engine - produces 115bhp and 184lb ft of torque. This motor drives directly into the single speed transmission, which, in turn, drive’s the A1’s front wheels. Between the engine and alternator pairing and the main electric drive motor is a simple clutch which allows the engine/generator to be engaged and disengaged from the rest of the drivetrain.
In urban mode, at speeds of up to 34mph, the A1 is driven by the main electric motor and battery pack and it promises an impressive 56 miles range on the battery.
If the battery pack is running low, electricity from the engine/generator is used to drive the motor. It’s possible to run up to 81mph in pure electric mode but, from 34mph, the clutch allows the three-cylinder engine to directly drive the transmission. The smaller generator motor acts as back-up to help reduce fuel consumption and to briefly assist during hard acceleration. Above 81mph, the combustion engine does all the work.

What is it like?

Surprisingly refined. We had the chance to try out what Audi engineers call a ‘pre-development’ prototype. The e-tron prototype was identical to a production A1 and did not seem to have lost boot space, which is impressive for such a small vehicle.
Pull the gear lever into ‘drive’ and the e-tron pulls away in silence on battery power and has the instant torque and seamless delivery typical of a car powered by an electric motor through a single-speed transmission. Above the 35mph, the new three-cylinder engine meshes into the transmission without the driver noticing - a product of the engine being spun up to the correct operating speed before the clutch engages - and it seemed very smooth and willing, although there is a distinctive, if distant, 'thrum' under hard acceleration.
Officially, this e-tron has 174bhp and a 0-62mph sprint time of less than 9sec. In reality, the A1 e-tron feels quicker than that. With both the engine and generator running, the A1 is deceptively swift on the open road and impressively smooth and refined at urban speeds. Audi’s new front-drive hybrid concept seems - even at this stage - superior to both the Prius’s conventional hybrid and the Volt’s range-extender with high-speed motor assist.
What’s most impressive is the relatively simple engine and electric motor layout and a single-speed transmission, which means it could also be less expensive than today’s production hybrids.

Should I buy one?

On this brief showing, yes. Audi wouldn’t confirm that this new type of hybrid transmission was a dead cert for production but it appears superior to many existing hybrid systems. It is less complex and more refined than the range-extender system in the Chevy Volt and the conventional hybrid drivetrain and CVT gearbox in the Prius.
And, although the new Golf family cars will be launched with a more conventional plug-in hybrid (which couples a diesel engine, electric motor, DSG gearbox and battery pack), it is likely that this compact and potentially less expensive set-up will be deployed in the new-generation Polo family of cars from 2015.
Audi A1 Dual-Mode Hybrid prototype
Price: n/a; Top speed: n/a; 0-62mph: 9.0sec; Economy: 56 miles (battery pack), 400 miles petrol engine only (est); Weight: n/a; Engine: 3-cyls, 1500cc, turbocharged petrol; Power: 128bhp; Torque: 147lb ft; Electric Motor 1: 67bhp/155lb ft; Electric Motor 2: 115bhp/184lb ft; Gearbox: single-speed