A married couple yesterday insisted boredom "would not be a factor" as they began a bid to make the most fuel-efficient drive yet around the world.
John and Helen Taylor will spend up to 14 hours a day on the road on a 70-day trip across 25 countries and four continents.
They aim to fill up the tank of their Volkswagen Golf FSI 1.6 just 50 times or less as they cover the 28,970km.
Mr Taylor (45) and his wife may cover up to 1,000km a day as they rumble over the world's highways.
But the couple insisted a selection of CDs, in-car games and their own company would see them through the many potentially tedious hours.
Shortly before they were waved off from the starting line at Waterloo Place in central London, Mr Taylor said: "There is no boredom factor. We have so many games and other activities in the car and I love my wife so it gives us a chance to talk."
The pair, who already have 34 fuel economy driving achievements under their belt, will have travelled across Europe, Asia, Australasia and America by the time they return to London in late March.
They conceded that one of the toughest challenges will be driving across the chaotic roads and rough terrain of Pakistan and India, but said that they were well prepared for any eventuality.
Mr Taylor said: "We do understand the lack of quality of some of the roads that I have driven on in India.
"We will also be helped by local people in some of these areas. But the key for us was to do 'an honest' drive and not just choose the easy route."
The couple will be accompanied by a crew travelling in two Volkswagen Passat estate cars. Equipment in the vehicles includes a GPS tracking system, satellite phones and a plethora of computer equipment as well as safety essentials.
Their car will use a new petrol developed by their sponsor, Shell, which may go on sale in the future. Mrs Taylor said; "We like to show people that in these hard environmental times they can save fuel."
The only breaks in their journey will be when they fly between continents and stop at their home in Melbourne, Australia, to attend their daughter's wedding.
The special fuel has already been transferred to depots around parts of their route while the rest will be flown out to other points of their journey at a later date. Updates on the couple's trip will be on fuelchallenge.com.