Toyota has added an all-new 1.33-litre Dual VVT-i petrol engine with stop-start technology to the Toyota Auris.

Toyota says that the new powertrain with stop-start results in 17% lower CO2 emissions (135g/km) and a 19% improvement in fuel consumption (48.7mpg combined cycle) compared to the previous 1.4-litre VVT-i unit.

The new engine has been developed with the benefits of Toyota’s motorsport experience and the transfer of compact and lightweight design. The new unit is 54mm shorter and 127mm narrower than the previous 1.4-litre VVT-i and weights 13kg less.

Toyota says the The result is a four-cylinder engine that is the same size as a three-cylinder 1.0-litre VVT-i. Its small bore and long stroke design gives a narrow block and reduces weight to give a very high power-to-weight ratio.

New pistons were developed with a smaller contact area to help produce quick and efficient combustion. Piston weight was also significantly reduced, from 280g to 180g – a 36% saving – which means they use less energy. For leaner combustion, an oil jet was integrated into the design.

Auris is the first model in Europe to benefit from Toyota’s stop-start technology and the firm says it provides a potential 15% improvement in fuel economy and CO2 emissions.

The engine is matched to a newly developed six-speed manual transmission, with ratios calculated to deliver the best possible balance of performance and fuel economy. The twin-shaft unit is 11% smaller and has 15% fewer components than the  five-speed unit, but has a higher torque capacity. Friction is reduced and the driver enjoys an improved gear shift feel. Using an extra gear compared to the transmission used in the previous Auris 1.4, VVT-i, it also gives more refinement at high speed.

From October 2009, the 1.33-litre Dual VVT-i engine will be manufactured at Toyota Motor Manufacturing UK’s (TMUK) factory at Deeside in North Wales.

Deeside currently produces 1.4, 1.6 and 1.8-litre VVT-i petrol engines at a rate of about 185,000 units a year. It also undertakes casting and machining of engine sets for export to other Toyota plants around the world.

Until Deeside production comes on stream Auris will be fitted with engines manufactured in Japan.

Five-door versions of Auris are also built in Britain at TMUK’s Burnaston plant, near Derby.