The secret to the 1.4 D-4D’s performance, is an improved torque curve – the engine now develops its peak torque of 205Nm from 1,400 rpm. And in every-day traffic, that makes all the difference, because it means that the Yaris will pull effortlessly from low speeds, making the car extremely confident in busy traffic conditions. It also means that the engine is less prone to stalling when pulling away.
It’s rare for an engine to deliver its maximum torque at such low engine speeds. In the case of the 1.4 D-4D, it was achieved by installing a smaller and extremely efficient turbo. It develops more boost pressure and does so quicker.
But the turbo wasn’t the only improvement. The fuel injection system was equipped with a larger supply pump, which now feeds diesel fuel into the common-rail at pressures of up to 180Mpa.
An NOx Storage Reduction (NSR) catalyst makes sure that the NOx emissions are kept below the stringent Euro 6 thresholds.
The upgraded engine develops 66kW / 90 DIN hp, which allows a very respectable 0-100km/h time of 10.8 seconds, and a top speed of 175 km/h. Very competitive figures, given the car’s low thirst – only 3.4 l/100km on the combined cycle.
But it is still the engine's low-end torque that will make the Yaris 1.4 D-4D a joy to drive, as it pulls willingly from any gear, and makes for an unseen responsiveness.