The Zipcar vehicle hire company ceased operating in the UK at the end of last year leaving their customers with few alternative choices.
It pointed its members to the CoMoUK website for more information on other car sharing options in their area.
One that might be of interest for Londoners is the Enterprise CarClub
It states that it operates in 30 London boroughs but their coverage of wards is low at present, as hereand it offers three membership options
Their vehicle locations are searchable by landmark or street.
