Actress Thandie Newton is fuming after a host of celebrities snubbed her attempts to convince them to go green. The CRASH actress wrote letters to the likes of Madonna, Jack Nicholson, Chris Martin, Robin Williams, Ozzy Osbourne, David Beckham, Michael Jackson and Tom Cruise, to persuade them to swap their gas-guzzling SUV's for more environmentally friendly cars. But Newton says, "I didn't get one letter back. I wasn't judgemental. It was like, 'In case you didn't know here are some facts about the environment and some reasons why it turns out 4x4s aren't that great to have in the city.'" The 36-year-old hasn't given up hope, and has set her sights on converting pal Oprah Winfrey. She says, "I was staying with Oprah recently and I suggested that she switches her whole fleet of cars. I really hope she does. It would do so much good."