The new BMW X6 Active Hybrid. Photograph: PR
It's the holy grail for motorists with a green conscience – a high-performance eco-friendly hybrid car. Well, that is what BMW will have us believe when it unveils its latest model at the Frankfurt motor show in Germany next week.
The show is likely to see a stream of new hybrids, cars that combine a combustion engine with an electric motor for improved fuel efficiency. And pole position is likely to be taken by BMW's ActiveHybrid X6, which it styles the "world's most powerful hybrid".
The new X6 goes from 0-60 mph in under six seconds and has a top speed of 130 mph.
But the company gives equal prominence to its pitch that the new hybrid is "eco-friendly", because its carbon emissions are 20% less than those of a regular X6.
For a few days last month you could read the same claim on the website of the Energy Saving Trust, the "impartial" adviser on energy efficiency set up by the British government.
But is it too good to be true? Of course. As one incredulous reader who spotted the story on the Trust's website pointed out: "The Trust is promoting a car as eco-friendly with emissions TWICE that of my 6 year old Honda Civic hybrid!"
The ActiveHybrid X6's official CO2 emissions rating with the European Union is 231 grams per kilometre. That compares badly with the EU's 2012 target for average emissions from new cars of 120 grams. It is also higher than the emissions from most of the new Lexus hybrid range and more than twice the emissions of a Toyota Prius, for instance.
The fact that it is better than the regular X6's rating of 299 grams per kilometre does not make it eco-friendly, I am afraid. The claim is greenwash.
I suspect we are going to see a rash of these high-performance high-emission hybrids masquerading as green. Back in the lab, BMW is developing a hybrid "supercar" that will reach 155 mph and 0-60 mph in less than five seconds.
Sure, hybrids are more fuel-efficient than the equivalent old models. The key is that the fuel does not have to be burned in inefficient surges as the car accelerates and brakes. It can be burned efficiently in a smooth flow, and the energy transferred to a battery that supplies the electric motor that drives the car itself. The battery can also make use of energy generated during braking.
But to call these high-performance models eco-friendly, or low-emissions as they burn up the autobahn is nonsense. They are, in reality, slightly less polluting gas-guzzlers.
The Energy Saving Trust seems to take a similar view. When my correspondent pointed out the dodgy nature of the car's green credentials, the offending story swiftly disappeared from its site. "Once we noticed it, we removed it straight away," a spokesman told me.
The rise of these new hybrids has important implications for green-minded legislators. For instance, it should increase the pressure on London's mayor to reconsider his blanket exemption from congestion charges for hybrid cars. Surely, only truly low-emitters should qualify.
Interestingly, the BMW PR promotes the idea that the driver of the hybrid X6 can "experience silence without coming to a stop", while the electric motor is running alone.
It sounds fun. But speaking as a pedestrian, I'm a bit scared at the idea of a car that can go from 0 to 60mph in less than six seconds without making any noise. Green or not, it sounds like a stealth killer.
