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The components that make up the e-tron’s hybrid powertrain are not unfamiliar. Its central means of propulsion remains a transversely mounted petrol engine, in this instance a 148bhp 1.4-litre, four-cylinder turbo petrol unit

Audi says the four-cylinder petrol unit used in the e-tron is one of its most advanced engines. The turbocharged motor, which uses an aluminium crankcase, is claimed to weigh just 100kg, but it isn’t compact enough to allow the fitment of the electric powertrain components without adjustment.

Matt Prior

Matt Prior

Road test editor
The engine uses advanced thermal management to deal with sudden demands from cold

Compared with the standard A3, the e-tron’s engine has been shifted by 60mm or so to the right to help make sufficient space for the extra ancillaries under the bonnet.

Its party piece, though, is thermal efficiency, particularly with regard to getting itself to an optimum working temperature even for those short, low-speed journeys during which it might not be called upon much.

The exhaust manifold, integrated into the cylinder head, is at the heart of its efforts, quickly warming the engine following a cold start. Should that prove insufficient for sudden moments of high load endured during kickdown, the e-tron’s motor features a number of special protective measures, including specially coated piston rings and bearings.

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Connected to the engine is a 101bhp electric motor, fed by a 125kg, 8.8kWh lithium ion battery mounted beneath the rear seats. Cleverly, the 34kg electric motor is sandwiched between the flywheel and a specially modified six-speed dual-clutch automatic transmission, with the motor’s power converter located overhead. 

This means that even in all-electric mode, drive arrives at the front wheels via proper gearbox ratios (spread to better suit a 0-2200rpm rev range), reducing the detachment felt at the throttle pedal with solutions such as Toyota’s planetary gearset.

When required, the engine is tow-started by the electric motor via a secondary clutch, which closes once it has reached the required speed – a process achieved within a few tenths of a second, according to Audi

Total system outputs are 201bhp and 258lb ft. That’s Volkswagen Golf GTI-rivalling and GTD-beating, but, predictably, the e-tron is compensating for something.

A typical A3 Sportback doesn’t weigh much more than 1200kg, but even Audi admits its hybrid is beyond 1600kg. We had it at 1645kg. That includes a generous amount of standard kit and doesn’t prevent the car from posting 176.6mpg combined as an official claim. 

No one will spot the weight gain from the outside, where the e-tron shares the Sportback’s dimensions and styling. Aside from the badges, headlights, rejigged air vents and an exhaust-concealing rear bumper, this is a five-door A3 – with a charging point hidden behind its grille. 

With plenty of other brands in the Volkswagen Group available to explore the potential for affordable, urban-focused electrified runarounds, Audi has been given the freedom to keep performance at the forefront of its thinking.

Consequently, save for the A1 e-tron, most of its concepts have resembled sports cars. The most practical application — up to now — has been the Audi R18 e-tron quattro, which used a Williams-designed flywheel accumulator system to win this year’s 24 Hours of Le Mans. 

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