The 2015 Yaris range offers 4 powertrains, two petrol, one diesel and one hybrid. The latter, which already accounts for a third of this model’s sales, was adapted to comply with the Euro 6 Standard and has benefited from adjustments that have now made its C02 emissions even lower, 75 g/km as opposed to 79.
Extremely economical (less than 3.3l/100) and clean (virtually zero nitrous oxide and particulate emissions), this powertrain offers unique qualities within the B-segment. The hybrid Yaris stands out for its silent running, comfort and easy handling, particularly in urban areas where the hybrid system allows the car to run solely in electric mode or with a limited - and therefore silent - use of the combustion engine. The automatic transmission ensures a smooth drive without any jerkiness, giving a comfortable and reassuring driving experience, both for the driver and his passengers.
As for the 3-cylinder 1.0 petrol engine, it has undergone a major revamp with a view to improving its performance, reducing its emissions and its noise and vibration levels. In compliance with the Euro 6 Standard, it achieves a level of thermal efficiency - the part of the energy contained in the fuel, which is converted into mechanical energy - of over 37%, which is an excellent result among mass-produced petrol engines that on average have a thermal efficiency of between 30 and 35%. The CO2 emissions of the 1.0 version have thus been reduced from 110 to 99 g/km and achieve 95 g/km with the Stop & Start system.
To achieve this, engineers have sought above all to optimise the weight/power ratio. From this aspect, the combination of the cylinder and the exhaust manifold head has reduced weight and improved compactness.
In order to reduce consumption while still maintaining performance, the compression ratio has been increased to 11.5:1, the intake ports and pistons have been redesigned to increase the tumble effect (vertical swirl in the combustion chamber) and piston cooling has been increased to delay knocking. Recirculation of the exhaust gas has been increased to promote combustion speed and reduce pumping losses, while the EGR valve now operates in conjunction with the VVT-i distribution system, the latter having also been adapted to suit the engine’s new characteristics.
Lastly, the level of the friction has been reduced by altering the valve actuator materials, the treatment of the surface of the pistons, the drive of the timing chain and the shape of the oil sump to ensure that the engine gets up to temperature quicker.