Green party Mayoral candidate Jenny Jones says she would save London households £1,500 over the next four years.
Jones made the pledge as she unveiled a range of new policies including subsidising fares though a new London-wide Pay-As-You-Drive road pricing scheme.
The Green campaign say the scheme would charge drivers a small amount for every mile they drive, and stress that it is a unconnected to the existing congestion charge zone.
Other proposals include refurbishing one million homes to improve their heat efficiency and supporting an expansion of street markets.
Jones says collectively these initiatives would lower the cost of living for Londoners.
Speaking outside City Hall on Wednesday, Jones said: “In the Green vision for London, the capital would become a more affordable place to live, work, travel and relax.
“During these times of increasing financial strain, only the Green Party is offering Londoners the possibility of tangible, realistic, everyday savings. In total our policies could save London households £1,500 over the next four years.
“For many, the money could be the difference between staying afloat and going under.”