We’re now five months into the six-month test of our Isuzu D-Max long-termer, and in this update, we’re going to assess the performance and refinement of Isuzu’s new 1.9DDi engine. The new Isuzu D-Max 1.9 engine is more fuel-efficient but lacks the torque of the old 2.5.

There was some disappointment when Isuzu announced that it would be retiring the 2.5 4JKA (2,499cc), which had been powering Isuzu pickups since 2002. The engine was renowned for its reliability and helped Isuzu earn the most reliable pickup title.

Isuzu D-Max 1.9 Engine Performance

However, with the Euro-6 emission standard kicking in, Isuzu has decided to introduce the cleaner and more efficient RZ4E engine. The four cylinders (80.0mm bore and 94.4mm stroke) have a total displacement of 1,898cc – making this by far the smallest engine in the sector.

Despite this, peak power – achieved at 3,600rpm – has increased slightly to 164PS (1PS more than the outgoing 2.5). Peak torque, however, has reduced to 360Nm (previously 400Nm) although the torque band is quite wide from 2,000 to 2,500rpm. Compared to other pickups in the range, the Isuzu D-Max feels slightly sluggish and underpowered.

Isuzu D-Max 1.9 Transmission

The engine is coupled to a six-speed manual transmission, although there is the option of a newly-developed six-speed automatic, which is very smooth although slightly hesitant at times. Isuzu has countered the reduction in torque by lowering the ratio to 4.942 and 2.430 for first and second gear, which is great when navigating steep incline and towing, but slightly frustrating when you want a quick turn of speed.

Isuzu D-Max 1.9 Fuel Economy

The fuel economy of the new Isuzu D-Max engine is a lot better at 45.6mpg on 4×2 models and 40.4mpg on 4×4 manual models. By downsizing and introducing a Lean NOx trap, Isuzu has managed to achieve the Euro-6 emission rating without the need of AdBlue.

Liam Campbell
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