BMW’s new full ActveHybrid system closely follows but does not entirely mimic the principle laid down by petrol-electric pioneer Toyota with its Synergy Drive set-up, as used by the second-generaton version of the ActiveHybrid X6 rivalling Lexus RX400h.

Both cars rely on a petrol engine as their prime means of performance; a 407bhp twin-turbocharged 4.4-ltire V8 in the BMW and a smaller 244bhp naturally aspirated 3.5-litre V6 for the Lexus.

Read the BMW X6 ActiveHybrid first drive

In both cars the petrol engine is supported by a pair of electric motors mounted within the gearbox, with each capable of electric only start up and propulsion over short distances for zero emission capability.

But while the ActiveHybrid X6’s motors generate 91bhp and 86bhp respectively, the RX400h’s are significantly more powerful at 164bhp and 67bhp.