It is certainly a vintage vehicle. And now Prince Charles's beloved Aston Martin DB6 is running on vintage too.

A nice little white from a vineyard in Wiltshire, to be precise.

As part of cutting his carbon footprint, the prince has converted the 38-year-old classic car - a 21st birthday present from the Queen - to run on 100 per cent bioethanol fuel distilled from surplus British wine.

Drink and drive: Prince Charles has converted his 38-year-old Aston Martin to run on bio-ethanol made from English wine

Aides said this was partly due to the pattern of Royal trips set by the Foreign Office. He has now doubled the target to a 25 per cent fall in emissions by 2018.

Converting the Aston Martin played a small but symbolic role. The Prince's chief aide Sir Michael Peat said: 'Charles only travelled two or three hundred miles a year in the Aston but he wanted it to be environmentally friendly. It just happened that our bioethanol supplier makes the fuel from surplus English wine.'

The car - which is kept at Highgrove and clocks up just 300 miles a year - averages ten miles a gallon, the equivalent of 4.5 bottles of wine for every mile.

At £1.10 a litre, the bioethanol is only slightly cheaper than conventional petrol, but is estimated to produce 85 per cent less carbon dioxide.

The grapes used for Charles's fuel have already been fermented into wine on an English vineyard near Swindon, Wiltshire.

Its owners bottle all they can, but cannot produce more than their EU quota. Rather than destroy the excess, the vineyard now sells it to the Gloucestershire biofuels supplier Green Fuels, where it is distilled.

The green prince has also introduced a raft of environmentally-friendly measures at his homes, such as reed bed sewage systems and wood-chip boilers at Highgrove and Birkhall, his Scottish residence.

He even tries to have his cows fed on grass rather than grain - to cut their flatulence and minimise their emission of the greenhouse gas methane.