By Jorn Madslien
Business reporter, BBC News
When Sainsbury's chief executive Justin King recently waved goodbye to his Maserati Quattroporte, he did so in favour of a relatively anonymous-looking limousine whose main claim to fame is fuel efficiency.
A sign, perhaps, that the boyish grocer is growing up? Or a hint at how fashions are changing?
In the past, Mr King, a self-confessed petrolhead, has favoured big-engined beasts.
This time he spent ages comparing their environmental credentials before choosing a company car.
In the end, he chose a long wheelbase Lexus LS600h L, a petrol-electric hybrid car that is essentially a much larger and considerably more luxurious version of Toyota's popular Prius, complete with a reclining leather massaging seat and bundles of electronic gadgets.
Mr King spends between 20 and 30 hours per week in the back seat, both between meetings in London and during his commute from the Midlands.
It's just like business class 15 years ago," Mr King grins as the driver steers the £88,000 limousine up London's Fleet Street towards Trafalgar Square.
"I work a 14 hour day," he says. "I work from the moment I get into this car till the moment I get out of it."
Mr King is excited by the car's hybrid technology and eager to explain how a screen on the dashboard indicates when the car's powerful petrol engine is pushing the car forward, and when it is charging the batteries that feed its electric engine.
"Now we're running on battery," Mr King says as the car glides quietly past Nelson's Column.
"The Lexus does some 30 miles per gallon, which is fantastic for a car like this. Normally, it would be 16 or 17 miles to the gallon."
Lexus has gone from strength to strength with its hybrid-powered luxury.
In the current atmosphere, its new environmental credentials have done what its reputation for reliability and refinement had failed to do for years, namely give the marque emotional appeal.
In recent months, the Japanese carmaker has won over a string of high level executive - including Mr King's main rival, Tesco chief Sir Terry Leahy - as well as many celebrities, including Sir Paul McCartney and his daughter Stella.
And when Tory leader David Cameron was asked at last autumn's CBI conference whether he had arrived on his bike, Boris Johnson-style, he responded that he had not, though he had arrived in a hybrid. His is a somewhat smaller version of Mr King's limousine, a Lexus official confides.
Demand for hybrid Lexus models created a six-month waiting list for the 600h before its launch in October last year, a situation previously unheard of for Lexus, which even after two decades of trying has failed to sell much more than 50,000 cars per year in Europe.
Last year, almost a third of its sales in Europe were hybrids.
The petrol engine powers the car and charges the battery
"Hybrid is Lexus brand defining technology," a company official says. "Only Lexus has hybrid, and we have three while others have yet to launch one."
For Lexus, hybrids have brought about a remarkable change in fortunes, which for its main rivals Audi, BMW and Mercedes is nothing if not irritating.
The German carmakers insist cars powered by so-called clean diesel often pollute less than the heavier Lexus hybrids.
"Diesel is a more honest technology," stresses Stefan Krause, BMW's outgoing sales and marketing director, in a recent interview with the BBC News website.
The point is not lost on Mr King, who insists he has not been taken in by the hybrid-badge's suggestion that the Lexus is "greener" than its rivals.
Making a comparison with the debate around food miles, he points out the importance of looking at the bigger picture. Overall carbon dioxide emissions from roses grown in Kenya and flown to the UK are lower than the emissions created by growing roses in European greenhouses, he explains.
Lexus sales in Europe
2004 - 24,893
2005 - 28,777
2006 - 50,570
2007 - 53,810
Similarly, given that Mr King uses his car both to commute from the Midlands and for city driving, in his case the overall emissions from, say, a diesel-powered Mercedes S320 would have been equivalent to those from his Lexus, he continues.
Moreover, he adds, when compared with its rivals the Lexus sometimes comes across as a bit sluggish because of the added weight - a couple of hundred kilograms - of its electric power packs.
"The area behind us, between the seats and the boot, is taken up by batteries," he says. "So there are some performance sacrifices."
The batteries also reduce the boot space, and Mr King's car only has four seats which means it is not always suitable as a family car for the weekend, he adds.
"It is great for a family of four but not if either of the children bring a friend along," Mr King says.
Not so green
But more importantly; although technology advances have helped reduce the emissions from some executive limousines, none of them could ever be described as "green".
Mr King wants his limousine to be discreet
Their sheer size means even the best in class are still emitting more than twice as much CO2 as many small cars.
Although currently exempt from the London congestion charge - along with all hybrid cars - Mr King will be charged from the autumn, when the London congestion charging system becomes a charge based on emission levels.
His car "just limbo's" below a 225 grammes of CO2 per kilometre travelled and as such will be liable for an £8 per day charge, rather than £25 per day.
Albeit a vast improvement when compared with similarly sized, similarly powered petrol-only limousines, it is hardly an environmentally friendly car.
But at least it is not a big, brash Rolls-Royce or Bentley - cars which although they can cost more than twice as much as the Lexus would still be eminently affordable for Mr King.
"I want to be as discreet as possible," Mr King says.
Perhaps he is coming of age after all?