Audi has updated the plug-in hybrid powertrain offered in its Q7 and Q8 models.

The Audi Q7 55TFSIe and the Audi Q8 55TFSIe are both now fitted with a larger 25.7kWh battery.

It enables a zero-emission range of up to 52 miles on the Q7 and 51 miles on the Q8, placing both cars in the 8% benefit-in-kind (BiK) tax band.

The plug-in hybrid powertrain pairs an electric motor with a 3.0-litre V6 petrol engine. Total system output is 394PS and 600Nm.

Drivers can select Hybrid or EV driving modes, which have both been recalibrated to boost efficiency. In EV mode the car will use the electric motor only, even when the accelerater is fully depressed. Hybrid mode is split between Auto and Hold. Auto relies on the driver using the car's sat-nav to manage the use of the battery effectively throughout the journey. When Hold is selected the car will save the current charge level for use later.

Audi has also updated the regenerative braking system. The electric motor now performs all light to moderate braking, which Audi says equates to around 90% of deceleration events in everyday driving.

A 7.4kW on board charger enables the battery to be fully recharged in less than four hours from a wallbox charger

UK pricing and specifications are yet to be confirmed.

Audi recently faclifted the Q7 and Q8 with revised styling and updated technology.