BMW has made a quad-turbo 7-Series

Meet the world’s most powerful six-cylinder diesel. It’s the new BMW 750d, and it comes with four turbochargers. Four. Like a Bugatti Chiron…

You want numbers, obviously. It’s a 3.0-litre straight-six engine, with peak outputs of 394bhp and 560lb ft. The latter figure arrives at 2,000rpm, and helps the big Seven to a 4.6-second 0-62mph time. That helps this BMW 7-Series keep up with the considerably slinkier M140i hot hatch.

Like all of BMW’s performance models, its “large and sustained wave of thrust” (their words) will continue until the spoilsport 155mph speed limiter comes into play.

As a diesel car, there are other, more sensible numbers to consider too. BMW claims CO2 emissions of 149g/km and fuel economy of 49.6mpg. In a regular turbodiesel, they would be unexceptional figures. In a quad-turbo, 1.8-tonne, hot hatch-quick limo, they’re damn good.

The engine comes mated only to all-wheel drive and an eight-speed automatic gearbox – probably good for keeping all that torque sensibly distributed – and it replaces BMW’s tri-turbodiesel engine.

Yes, three turbos are never enough, it seems. That old engine used one big turbo and two smaller items, but its successor goes for four small turbos (they’re quicker reacting, that way), two of them working at low pressure, two at high pressure.

They have a finely choreographed routine which means all four are rarely working all at once, but which does mean there’s response at the top of the rev range as well as its lower reaches.

The 750d xDrive (and its long-wheelbase 750Ld spin-off) arrive in July, as will the new 740e iPerformance. It’s a plug-in hybrid 7-Series, mating a 2.0-litre four-cylinder petrol engine to an electric motor, with 322bhp the result. It will manage around 30 miles on electric power alone when you’re being careful, and hit 62mph in 5.4 seconds when you’re not.

While there’s no price for the 750d yet, the 740e will start at £68,330, with all-wheel drive and long-wheelbase versions optional. And the iPerformance badge will become familiar, too: it will also be applied to BMW’s other hybrid models, the BMW 225xe and BMW 330e included.