The congestion charge has been heavily criticised by some opponents. They argue that the public transport network has insufficient spare capacity to cater for travellers deterred from using their cars in the area by the charge. Further, it is said the scheme will hit poorer sections of society more than the rich, as the charge to enter the zone is a flat £10 for all, regardless of vehicle size. The charge has proved controversial in Outer London, where it has encouraged commuters who previously drove into Central London to instead park at suburban railway or underground stations. This has led to the widespread imposition of controlled parking zones in these areas, at the expense of local residents.
Steven Norris, the Conservative Party candidate for mayor in 2004, has been a fierce critic of the charge, branding it the 'Kengestion' charge, and pledged to scrap it if he became mayor in June 2004. He had also pledged that, if elected, he would grant an amnesty to anyone with an outstanding fine for non-payment of the charge on 11 June 2004. In an interview with London's Evening Standard newspaper on February 5, 2004, Conservative leader Michael Howard backed his candidate's view by saying "[the charge] has undoubtedly had a damaging effect on business in London." Liberal Democrat candidate, Simon Hughes however supported the basic principles of the scheme. Amongst some of the changes he proposed included changing the end time from 6:30 p.m. to 5 p.m.; automatically giving all vehicles five free days a year so as not to affect occasional visitors.
In 2005 the Liberal Democrats claimed that Capita had been fined £4.5 million for missing the targets set for the congestion charge, that was equivalent to £7,400 for every day that the charge had existed. The London Assembly Budget Committee 2003 report on the company criticised the contract with Capita as not providing value for money. It was reported in July 2003 that TfL agreed to bail-out Capita by paying them £31 million because they were making no profits from the project, and that their most critical problem was the 103,000 outstanding penalty notices not paid. Capita was also the company that won the 'Most Invasive Company' award in the Privacy International 2003 Big Brother Awards.
Capita have employed subcontractors including Mastek, based in Mumbai, India, who are responsible for much of the IT infrastructure. Due to the wide spread around the globe of sub-contractors and because some data protection regulations vary from country to country, the scheme has prompted concerns about privacy from technology specialists.
Towards the end of 2006, the Mayor proposed the introduction of a variable congestion charge. Similarly to vehicle excise duty (VED), it would be based on emissions of carbon dioxide in grams/km. This would reduce or eliminate the charge for small and fuel-efficient vehicles, and increase it to up to £25 a day for large, inefficient vehicles such as SUVs, large saloons and compact MPVs with a Band G VED rating, that is, emissions of > 225 g/km of CO2. Electric zero-emissions vehicles are already exempt from the charge.