BMW has expanded the powertrain line-up of the G05 X5 and G06 X6 with a new xDrive40d variant, which features the newer B57 3.0 litre straight-six turbodiesel engine. The new mill replaces the N57 mill used in the previous generations of the SUVs, providing more output in the process.
The B57 engine features BMW’s TwinPower Turbo tech, which sees the use of a two-stage turbocharging system with variable turbo geometry for high- and low-pressure stages. It also gets common rail piezo direct fuel injection that is capable of up to 10 injections per cycle, with the injectors feeding fuel to the combustion chamber at a pressure of up to 2,700 bar.
According to the German carmaker, the oil burner develops 340 PS (335 hp) at 4,400 rpm and peak torque of 700 Nm from 1,750 to 2,250 rpm. This is a considerable gain over the previous N57-equipped xDrive40d variants, which provided 313 PS (309 hp) and 630 Nm.
The standard transmission here is an eight-speed Steptronic automatic unit, which is paired with BMW’s rear-biased xDrive all-wheel drive system. Both the X5 and X6 xDrive40d models will sprint from a rest to 100 km/h in just 5.5 seconds.
Also present is a mild hybrid system that consists of a 48-volt starter generator, which provides an additional electric output of 11 PS (11 hp or 8 kW) to promote spontaneous power delivery and effectiveness of the drive system.
The latter sees a better refinement of the engine idling start-stop function as well as supporting the vehicles’ coasting function. During coasting phases, the engine is disconnected from the transmission, and this function is present in both Comfort and Eco-Pro drive modes.
To ensure compliance with the Euro 6d emission standard, which won’t take effect until the start of 2021, the xDrive40d offerings are equipped with a two-stage NOX exhaust gas treatment that has been further developed to feature an oxidation catalyst converter and a selective catalytic reduction (SCR) coating on the particulate filter. For optimum reduction of nitrogen oxide emissions, a second dosage unit has been integrated at the outlet of the SCR system.
Efficiency-wise, the X5 xDrive40d has a combined fuel consumption of between 6.4-5.9 l/100 km and CO2 emissions of between 167-154 g/km. Meanwhile, the X6 xDrive40d’s fuel consumption is rated at 6.2-5.8 l/100 km, with CO2 emissions of between 164-153 g/km.