Environmental activists are targeting 4x4 drivers with the offer a free "mudwash" for their vehicles.
Members of the Alliance Against Urban 4x4s are providing the "service" in London, Birmingham, Manchester, Reading and Basingstoke.
The group has said it can offer looks including "Gloucestershire Gunk", "Cumbrian Crud" and "Surrey Slurrey".
The alliance said it hoped the move would make drivers think whether their choice of car was appropriate.
Spokesman Blake Ludwig said: "We are challenging urban 4x4 drivers to let us get their cars dirty for them because they will never get them genuinely muddy if they only drive to their child's school or the supermarket."
The group will also be asking people to sign their petition to the Government calling for higher taxes for 4x4s and a ban on four-wheel drive adverts.
Some motoring groups have said the cars are popular because they are "useful and flexible".
Paul Everett, of the Society of Motor Manufacturers and Traders, said: "The environmental performance of your average 4x4 is no worse than a large saloon or people carrier.
"In many cases the safety performance of these vehicles is better than many other vehicles on the road."