Fifteen of its members were arrested for handcuffing themselves to unfinished vehicles at the manufacturer's Solihull factory.
The move was a protest against 'gas-guzzling' vehicles and the 'aggressive marketing' of 4x4s for 'urban fashion use'.
Cancer Research UK came sixth in the NGO Watch chart for May, while Breast Cancer Care failed even to make it into the top ten.
International issues dominated the NGO agenda, said Infonic researcher Toby Lincoln.
'Global warming and the human rights abuses in Darfur and Iraq were joined by concerns over the crackdown on demonstrators in Uzbekistan and the Make Poverty History campaign,' he added.
Meanwhile, Amnesty International - which came fifth - criticised the US base in Guantanamo Bay as the 'Gulag of our times'.
NGO WATCH - May 2005
Ranking NGO No of mentions
1 Greenpeace 100
2 Red Cross 90
3 Human Rights Watch 74
4 Friends of the Earth 69
5 Amnesty International 62
6 Cancer Research UK 56
7 Oxfam 51
8 Age Concern 48
=9 UNICEF 43
=9 WWF 43