AUDI has launched an emissions-busting A4 by transplanting its Le Mans-developed FSI common rail petrol technology into a 2.0-litre engine.

The new technology achieves the seemingly impossible feat of boosting power while improving fuel consumption and reducing carbon dioxide emissions.

The CO2 emissions of the A4 2.0 FSI are 170g/km, 20g/km lower than the standard A4 2.0, while the new engine's fuel economy has improved by about 5mpg and power by 20bhp.

The 2.0 FSI engine carries a £1,000 premium over the standard 2.0-litre model, costing £19,565 on-the-road for the saloon and £20,695 for the Avant. However, despite its higher price, the improved emission of the FSI put it two tax bands lower under the new benefit-in-kind tax system, delivering a tax saving of about £100 a year for a 40% payer.

The direct injection petrol engine works in a similar way to common rail diesels by injecting fuel at high pressure directly into the cylinder, rather than into the intake manifold as on most petrol engines.