Toyota has unveiled two all-new small-displacement petrol engines designed to make its next-generation compact cars at least 10 per cent more fuel efficient than its existing models.
The Japanese manufacturer plans to introduce 14 variations of its all-new 1.0-litre three-cylinder and 1.3-litre four-cylinder petrol engines, the first of which will launch in 2015.
While most car makers are turning to downsizing, direct injection and turbocharging to improve the efficiency of their engines - General Motors, for example, revealed a new downsized range of motors just a few weeks ago - Toyota is taking the unprecedented step of employing the Atkinson burning cycle and combining it with high compression ratios and a rapid combustion process.
Toyota has only ever employed the Atkinson cycle in its hybrid vehicles, though the new engines will not be teamed with electric motors. The burning process of the Atkinson cycle improves fuel efficiency by keeping the intake valve open momentarily during the compression stroke, though its downside is reduced power and torque.
Toyota claims to combat this partially by running high compression ratios – 11.5 for the three-cylinder engine and 13.5 for the four-cylinder, just short of the 14.0 achieved by rival Mazda.
Other innovations designed to improve fuel efficiency further include a newly shaped intake port and a cooled exhaust gas recirculation system. The 1.3-litre engine also features Toyota’s Variable Valve Timing-intelligent Electric (VVT-iE) technology in the pursuit of improved combustion and reduced loss. The duo will also be available with stop-start technology.
Combined, Toyota claims all of the fuel consumption reduction technologies will make vehicles powered by the larger engine approximately 15 per cent more efficient that existing models, and those equipped with the smaller unit up to 30 per cent more efficient than current cars.
Toyota has not announced which vehicles will get the engines, though they are expected to launch initially in compact models for the Japanese market. The globally popular Yaris and Corolla models would be obvious early recipients of both engines.