Audi cylinder shut-down cuts fuel use

But it is unlikely to make it to Australia in the A1 Sportback. The five-door hatch was launched in Europe last week with a 103kW/250Nm 1.4-litre four-cylinder engine that shuts down two cylinders when the engine is under low load or coasting.

Audi says the "cylinder on demand" deactivation reduces fuel use by 0.4 litre/100km, while the idle stop/start system trims another 0.2 litre/100km for a combined fuel consumption of 4.7 litres/100km.

Australian spokeswoman Anna Burgdorf says the frugal engine isn't on the local radar and won't be unless buyers demand it.

"At this stage we don't plan to bring that car," she says. "Technology of that kind comes with a premium ... there's a fine line between a premium subcompact car and a car that's just too expensive."

It's a different story with the base 1.2-litre turbo engine, which would give Audi an entry model priced under $30,000.

"We're interested in it and are looking at the business case for it but it only comes with a manual gearbox," she notes. "Most (75 per cent) A1 sales have been with the S-tronic automatic transmission so that something we have to consider."

The A1 Sportback is expected to go on sale in late June with an estimated price for the entry level car of just over $30,000.

CYLINDER ON DEMAND

Audi showcased its cylinder deactivation system last year on the 4.0-litre V8 destined for the top-range S models. The tech has now flowed down to the A1 Sportback and is expected to be introduced across the Audi model range, though the company won't comment on timing. Two cylinders are disabled on the A1 when the engine is running from 1400-400rpm under light loads.

It operates via camshaftt sleeves known as cam elements that have two profiles - a regular mode and one that rotates over the inlet and exhaust valves without activating them. As the accelerator is depressed and engine load increases electromagnets slide the sleeves to enable all four cylinders.

The system is designed not to work under braking or when the car is coasting downhill to maximise engine braking. On the road there is a barely perceptible change in the engine note when the system cuts two cylinders and only a miniscule jolt as it returns to normal running that can't be noticed unless the driver is actively trying to find it. There's no vibration when it is running on two-cylinders, which Audi attributes to the dual-mass flywheel and changes in the engine bearings.