East Cambridgeshire Liberal Democrats are fighting a council clampdown on advertising on the region's taxis for fear it will put passengers' lives at risk.
They are worried after the council decided to get tough with cabbies who splash their company logos and contact details across their cars.
And they have warned they could lose their licences if they don't stick to the rules and restrict adverts to the front doors only.
But Liberal Democrats fear that the move could lead to passenger confusion and result in people climbing into unlicensed vehicles.
They recalled the case of Cambridge university student, Sally Geeson, 22, who was strangled after getting into a car on New Year's Eve 2005 believing it to be a taxi.
Sue Austen, Ely West councillor and a member of East Cambridgeshire District Council's licensing committee, said: "Some of the taxis have a flash across the side doors and boot and it makes it very clear to passengers that it is a licensed vehicle.
"It needs to be obvious which cars are officially licensed - we can't rely on people being able to read the licence plates. There is a real danger that people could be confused which would result in them climbing into an unlicensed vehicle.
"The council's action is so petty. We want to encourage visitors and tourists to come to Ely yet we are making it difficult for them to get round the city."
Taxi drivers have been told they have until January to adhere to the rules which state full colour adverts no larger than 28 inches by 12 inches can be fixed to the front doors of the cabs.
They are fighting the move and drivers with Ely company, A10 Taxis have launched a petition.
Cllr Austen added: "If they don't remove the advertising they have been told they are in breach of their licence conditions and could lose their licences."
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