A Swiss solar-powered car delivering an environmental message has ended a 17-month, 52,000-kilometre around-the-world trip.
The small two-seater, carrying chief United Nations climate official Yvo de Boer, glided up to a building in the Polish city of Poznan, where delegates from some 190 countries are working toward a new treaty to control climate change.
"This is the first time in history that a solar-powered car has travelled all the way around the world without using a single drop of petrol," said Louis Palmer, the 36-year-old Swiss schoolteacher and adventurer who made the trip.
The vehicle, which hauls a trailer of solar cells, began its 38-country odyssey in the city of Lucerne and is capable of travelling up to 90km/h.
Developed by scientists at Swiss universities, the so-called "solar taxi" covers 300 kilometres on a fully charged battery. UN secretary-general Ban Ki-moon has been among the passengers.
Palmer said he lost only two days to breakdowns during the journey.
"This car runs like a Swiss clock," he said.