However, for those taking the plunge while wishing to keep as much cash in the bank as possible, petrol options can be ruled out straight off the bat. Even if you cover an average number of miles you’re likely to be looking at some big fuel bills. BMW claims 32-35mpg for six-cylinder 740i models, depending on specification, while the 750i doesn't fare quite so well with an average of 26-27mpg.

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The (now discontinued) M760Li really is in a class of its own for high fuel consumption. BMW claims, 20.8-21.6mpg, but the average prospective buyer of a V12 powered BMW these days is unlikely to be bothered.

Under WLTP testing, the entry-level 730d returns up to 51.4mpg. The extra weight of the long wheelbase 730Ld doesn't harm economy much, with a maximum quoted figure of 50.4mpg. Adding xDrive four-wheel drive imposes a bigger penalty, with a best of 47.9mpg quoted.

Go for the 740d which has xDrive as standard, and the difference between it and the 730d xDrive is marginal, with a best quoted figure of 47.1mpg, or 46.3mpg for the long wheelbase version.

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In terms of efficiency, the best performer is the plug-in 745e. Its battery assisted drive system has a best quoted economy of 141.2mpg, while the 745Le xDrive version manages 134.5mpg. How close you get to those figures will depend entirely on how often you can charge the battery up, but the 745e's emissions will be more relevant to company and fleet users. While the 730d has emissions ranging from 144-170g/km, the 745e manages 41-56g/km, depending on wheel size and drive layout, which means low Benefit In Kind rates. BMW claims a maximum range of 34 miles on electric power only, up to speeds of 68mph.

You’ll have to pay extra for a rapid charging cable, however – BMW only provides a 13-amp cable as standard. An array of optional extras related to charging are offered, including home wallbox installation.

Insurance

Insurance premiums will be predictably expensive as all models are in group 48-50.

Depreciation

Unsurprisingly for a large and expensive car residual values aren’t great, with most of the line-up predicted to retain around 32 to 38 per cent of purchase value after three years/36,000 miles. The powerful petrol 750i models fare worst, with the best option either the 745e or 745Le plug-in hybrid.