There are those who may wonder why a company apparently fixated on reducing the car’s environmental impact and generally turning a brighter shade of green should decide to introduce a 206mph two-seat roadster with 5.4litre 617bhp engine that pumps out some 350g/km of CO2 emissions from its four noisy exhaust pipes.

The answer is simple: because it can. Working with McLaren, Mercedes-Benz is demonstrating its ability to sell £350,000 of supercar to the super-rich. A touch hypocritical? Possibly — but in the real, commercial world, Mercedes is also demonstrating the span of its technological capability.

That demonstration started with the SLR Coupé in 2003 and it continues with the Roadster, which is on sale now and which may look just like the coupé with its roof chopped off, but more than 500 components are new or modified.

Driving the SLR is a strange experience. Mercedes says that it “unites the legend of the successful SLR racing models of the 1950s with the innovative technology of modern F1 vehicles from the Vodafone McLaren-Mercedes team”.

And it does. Despite its advanced technology, carbon-fibre bodyshell and highly sophisticated chassis and engine, there is something old-fashioned about it.

The SLR seems big and its controls have a curious feel. Unlike most modern cars, you do not just climb aboard and drive it rapidly with total confidence. It takes time to understand its strange, sometimes dead-feeling steering, very powerful ceramic brakes that squeal and need a hefty push, a gearbox that has settings for various shift points and engine speeds – and a supercharged, bellowing engine.

If you reckon that your car is quick, consider the SLR’s acceleration figures: 0-62mph, 3.8sec; 0-125mph, 10.9sec; 0-186mph, 30.8sec. That’s quick. Once my cerebral software had adjusted to all this, confidence built and the SLR’s capability blossomed. On fast, winding roads it became addictive and the more I probed its capabilities, the more I wanted to stretch them.

But hang on a minute, I am not supposed to feel like this. I am supposed to be a reasonably sensible critic of what the motor industry serves up, including energy efficiency, value for money, practicality and safety.

Yet here I am being seduced by a car that, by any stretch of the imagination, is absurd in absolutely everything but its technology.

I decide that I ought to switch off its fuel guzzling, emissions generating engine, park it, close its roof (it has to be tugged down to the windscreen like something out of the 1980s), lock it and walk away.

And I will. After one more drive . . .