A trio of emission-free electric vehicles have pulled up silently in Geneva, completing a trip around the world to promote green energy.
An Australian three-wheeler, a German scooter and a Swiss Monotracer motorcycle arrived at the UN's European headquarters in the Swiss city.
They had taken 188 days to cover 27,000km (16,800 miles), 80 days of which were actually spent driving.
The main obstacle they faced was recharging in remote areas.
"It was very hard in some places, certainly for our team members in Russia and China," said Alexandra James, one of the 12 volunteers who took their turn driving the bright green Australian two-seater, dubbed Trev.
"They were wiring straight into the power supply in certain situations because it was the only way to get a reliable power source - it was a challenge," she told AFP news agency.
Sylvie Motard, of the UN Environment Programme, said the "Zero Race" had shown that cars powered by clean, renewable energy could be "as effective as petrol-driven vehicles but without emissions".