Campaigners against so-called Chelsea Tractors are calling for the London congestion charge to be raised to £20 for gas-guzzling cars. Hundreds of members of Greenpeace and the Alliance Against Urban 4x4s are hitting Goodge street today to lobby Londoners on the new proposal, while the groups have hung a huge banner across Marylebone High street that says: "CHARGE 4x4s £20".