The world’s only quad-turbo diesel engine will cease to exist after September 2020.

BMW’s quad-turbodiesel engine production will come to an end later this year. It seems the engine has become too expensive and too complicated to be viable any longer. Its use was also limited to 5 models, making it difficult to scale.

The B57S quad-turbodiesel first went into production in the 2016 750d but most will know it from its application in the X5 and X6 50d models, and the X7 50d.

Delivering huge torque (760 Nm) it was perfectly suited to large SUVs, accelerating the X5 variant to 100 kph in just 5.2 seconds with a top speed limited to 250 kph. Efficiency was what the engine was designed for, claiming 7.2L/100 km and with the 80-litre tank fitted to the X5 it was theoretically possible to clock up 1 111 km on a single tank of diesel.

We had the chance to sample the super rare M550d Touring (the same quad-turbodiesel engine) during a trip to Spain where we tested the M2 Competition models on the Ascari circuit. Over the tight and twisty corners outside of the circuit, the punch from down low was a notable highlight as the huge station wagon barrel-rolled its way from one tight bend to the next. Not as quick as the lighter M2 Competition, but certainly mind-bogglingly quick for a diesel.

BMW Romania has sought to give the quad-turbodiesel unit a send-off by producing a limited number of Final Edition models which aside from an array of options fitted come with 'Final Edition' inscribed on the door sills.

This is a Romania only model, but it is expected there may be further swansong variants as the B57S departs on its final tour.

Check out out video review of the X5 M50d here

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