Driven: BMW 5-Series 535d

But just hold on a moment. BMW's new 535d, on sale in mainland Europe from September and the UK shortly after that, is not a 3.5-litre car at all. It's still a 3.0-litre, despite its name - but judging by the power and torque it produces and the way it goes, it could easily be a 3.5. Or a 4.0, for that matter.

The key is its twin-turbo forced induction. A typical twin-turbo installation on a V6 has one turbocharger per bank, but BMW doesn't do V6s because they aren't smooth enough. (A straight-six is perfectly balanced and theoretically vibration-free.) So here we have a different idea, along the lines of the sequential turbo system used by Mazda in the final-generation RX-7.

Before explaining how it works, I should reveal the results: 272bhp (up from the 530d's 218bhp), 413lb ft of torque (369), 0-62mph in 6.6 seconds despite the standard-fit, six-speed automatic transmission, and a maximum speed limited to 155mph. And 391lb ft of that torque is on tap from 1500rpm, barely above tickover.

This is another example of today's mega-diesels, able to produce more power than a same-size petrol engine as well as the expected annihilation in the torque delivery. There's a perfect example of this right inside BMW-land, in the shape of the company's new 3.0-litre petrol engine to be fitted first to the 6-Series. Its power is 258bhp; that's impressive enough in its own right, but these diesels are creating a whole new set of rules.

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