IT'S a recognised fact - you can't afford to be mean if you want to go green.
Alternatively-fuelled cars can cost significantly more than their conventionally-powered counterparts - one of the reasons, perhaps, that sales of electric and hybrid vehicles have been slow to take off.
But there's one new vehicle which bucks the trend - and it comes from a very surprising source.
The new Bentley Bentayga Hybrid is the least expensive version of the luxury car maker's big SUV, costing some Â£6,400 less than the cheapest petrol only version.
OK, so at Â£130,500 this is still one stratospherically expensive motor car for most of us - but for those who want to go green while enjoying all the sumptuous quality and luxury a Bentley can provide, it's great news.
The reason for the lower starting price is largely down to the fact that the Hybrid comes with an adaptation of an existing Volkswagen Group petrol/electric power train.
The set-up, which can also be found in other VW Group cars including the Porsche Cayenne, combines battery power with a three-litre V6 petrol engine - the smallest engine ever used in a Bentley and a significant step down from the eight and 12 cylinder lumps which power the pure petrol-engined Bentaygas.
Which, of course, means that it's not as quick as its stablemates, although a 158mph top speed and 0-60mph acceleration time of 5.5 seconds plus more than respectable mid-range acceleration should be plenty enough for most needs.
That, however, is not what this particular Bentayga is all about. What potential buyers will want to know is what difference the 126bhp of electric motor power and heavyweight, underfloor-mounted battery pack make to the driving experience and whether or not it will up their green credentials at the golf club bar.
Press the start button on the central console, move off and the silence is even more golden than the Bentley norm. If you could actually measure silence, the Bentayga Hybrid would be off the scale when driven in electric mode.
Petrol mode soon kicks in, however, and the only differences can be seen in the instrument and touch screen displays. It's still amazingly quiet, albeit with some road noise on less than perfect surfaces.
The Hybrid has three driving modes - EV Drive, Hybrid and Hold - and comes with a revised infotainment screen and instrument panel. The tachometer is replaced with a dial showing when the car is operating in EV Drive, or engine speed if the petrol engine is operating. The infotainment screen can display energy flow in each of the three electric modes.
And the Bentayga Hybrid has one very clever and exclusive trick up its sleeve - the electric drive system is linked to the car's satnav to calculate the best usage of electric motor and engine for every journey.
Inputting your destination into the navigation system tells the car to automatically engage the correct electric mode for each part of the journey calculating the most efficient use of battery charge and saving electrical power for sections of the journey where it is most useful - such as when arriving in the city at the end of your drive. The satnav display itself provides a real-time radial indication on the map showing how far the car can travel in any direction on electrical power alone.
Bentley claim an all-electric driving range of up to 27 miles depending on conditions with recharging at a high speed charger taking two and a half hours - or seven and a half if you plug in at home using the charger and cables supplied with the car.
So just how green is the Bentayga Hybrid? Compared with other Bentleys it's positively Sherwood - with tree-hugging CO2 emissions of 75g/km compared with the Bentayga V8's 290. In our brief mixed-roads first drive we achieved just over 30mpg - not bad for a weighty luxury car by any means.
For the rest, the Hybrid is a true Bentley in every respect. It shares its eight speed auto gearbox, permanent four-wheel drive and four on-road modes - Sport, Bentley, Comfort and Custom - with the rest of the range and boasts a smooth if slightly firm ride, exceptional handling and all the handcrafted hide, wood laminate and luxury bells and whistles you would expect.
As the company's first venture into greener motoring it represents a positive start - but it won't be the last. The Crewe company plans to hybrid versions of all its current model within the next three years and a pure electric model by 2025. Watch this space!