BMW has just unveiled the new X5 xDrive40d and X6 xDrive40d models that come outfitted with a straight six-cylinder diesel engine and mild-hybrid technology.

The diesel powertrain used by both models displaces 3.0-liters and includes a two-stage turbocharging system and Common Rail piezo direct fuel injection. All up, the engine delivers 335 HP (340 PS) at 4,400 rpm and 516 lb-ft (700 Nm) of torque between 1,750 rpm and 2,250 rpm.

Both the X5 xDrive40d and X6 xDrive40d couple this engine with an eight-speed Steptronic transmission and intelligent BMW xDrive four-wheel drive technology. Assisting the 3.0-liter straight-six diesel is a 48-volt starter-generator that provides an extra 11 HP (11 PS). Both models can sprint to 62 mph (100 km/h) in 5.5 seconds.

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The starter generator gets its power from the SUVs‘ 48-volt battery that also supplies all-electric driving functions via the 12-volt vehicle electrical system. The battery is charged through the recuperation of energy during acceleration and braking. BMW says the starter generator also provides spontaneous and low-vibration starting and re-starting of the engine when the Auto Start/Stop or “sailing” functions are enabled.

The “sailing” function (also known as coasting) not only disconnects the engine but also switches it off entirely. To make use of this function more frequently, it is now no longer only available in Eco-Pro mode, but also in the Comfort mode.

The BMW X5 xDrive40d has a claimed average fuel consumption of 36-39 mpg (5.9-6.4 l/100 km) and combined CO2 emissions of 154-167 g/km. The X6 xDrive40d returns 38-40 mpg (5.8-6.2 l/100 km) and combined CO2 emissions of 153-164 g/km. BMW hasn’t said when the vehicles will hit the market nor how much they will set customers back.