The big barges favoured as executive transport don’t generally have much to commend them from a sustainability perspective but, given that they are going to be built anyway, it’s good to see how much clever thinking has gone into the latest BMW 7-Series.
While it’s normal for high tech innovation to dribble down from executive cars to the following generation of more popular models, in this instance the journey has been done in reverse. Carbon fibre structural tech pioneered by the BMW i3 EV has been put to work across the latest 7-Series range, which relies on a patchwork mix of carbon, aluminium and extra-high-strength steel to hold everything together.
The car’s bonnet, boot and door skins are made of aluminium alloy, while 50% of the aluminium used in cast-alloy parts is recycled. Even some of the carbon parts are made using offcuts from other sections, BMW says.
The result is a lot of weight saving, meaning the latest 7-Series cars are about 130kg lighter than the previous models, despite increases in standard kit.
It’s all relative, of course, and the 7-Series still hovers in the vicinity of two tonnes, checking in between 1,830kg and 2,075kg before anyone climbs aboard, depending on trim level and the choice of short or long wheelbase chassis.
The heaviest of the lot is, arguably, also among the most efficient. The freshly launched 740Le xDrive is a plug-in hybrid capable of covering about 25 miles on batteries alone, probably sufficient to get from boardroom to bedroom in many cases.
Electricity is stored in a 9.2kWh lithium-ion battery under the rear seating, with 80% of the capacity available for silent running, after which the car reverts to petrol-electric hybrid mode. The battery can be recharged in just under four hours using a standard 3-pin socket, while a BMW wallbox will take about an hour less.
Perhaps surprisingly, there are only four cylinders under the bonnet. The 2.0-litre engine produces 255bhp and combines with an 83kW (111bhp) electric motor to provide an overall peak power of 322bhp, with a robust torque potential of 500Nm.
This allows the long-wheelbase, 4x4 hybrid to reach 62mph in just 5.3 seconds. The motor is integrated into the automatic 8-speed torque-converter transmission, allowing it to propel the car with the engine switched off at up to 87mph.
A rear-wheel-drive, shorter wheelbase variant of the car, the 740e, is somewhat lighter and can travel a little further on battery power alone as a result – up to about 27 miles in fact. It is also noticeably cheaper, starting at £68,330 compared to £74,880 for the longer four-wheel-drive 740Le xDrive.
Those prices mean neither edition will get any kind of handout from the plug-in car grant, which ceases to contribute to cars costing more than £60,000. Both will, however, qualify for free passage into London’s central congestion zone. With official CO2 ratings or 52g/km for the 740Le xDrive and 49g/km for the 740e, both slot very comfortably within the 75g/km threshold for exemption, though both will probably slot less comfortably into the average London parking bay.