Toyota reveals fuel-saving engine plans

TOYOTA is developing a series of new petrol-powered engines using technology from its hybrid powertrains to improve fuel efficiency in some of its models by at least 10 per cent.

The Japanese car-maker says the engines will produce at least 14 different variations that will feature in models that are set for mid-life updates or redesigns by 2015.

One of the engines is a 1.3-litre petrol unit using the Atkinson cycle that Toyota typically matches with its hybrids, allowing for an increased expansion ratio while reducing waste heat through a high compression ratio (13.5) for better thermal efficiency.

Other measures Toyota is taking to improve efficiency include the use of a newly-shaped air intake port to generate a strong tumble flow in the cylinder and a cooled exhaust gas recirculation system matched with Toyota’s ‘Variable Valve Timing-intelligent Electric’ (VVT-iE) technology for improved combustion.

This will give the engine maximum thermal efficiency of 38 per cent and the various fuel-saving technologies, including idle-stop, will mean a 15 per cent improvement when compared to current Toyota models.

The second engine is a 1.0-litre unit which is being co-developed by Toyota-owned car-maker Daihatsu. According to Toyota, this unit has achieved maximum thermal efficiency of 37 per cent and thanks to the aforementioned efficiency measures, will improve fuel economy by 30 per cent over existing models.

Toyota is yet to confirm which of its models will feature the new engines, but they are likely to first surface in Japanese-market compact models.

One contender for the local market could be the Yaris light car which is due for a mid-life upgrade later this year.

A number of Toyota’s rivals are also developing more efficient powertrains, with Honda’s Earth Dreams engines using turbocharging and direct-injection technology, while fellow Japanese brand Mazda combines fuel injection and high combustion ratios for its SkyActiv engines.