Between April and June this year the Met were called to more 70 reports of cars being stolen each day.
But over that period just 56 cases (0.7 per cent) saw a suspect charged, figures from the Home Office scrutinised by the Liberal Democrats revealed on Monday.
The Metropolitan Police had the highest proportion of unsolved vehicle thefts in England and Wales.
Richmond Park MP Sarah Olney said: “There is a car theft epidemic across London. Criminal gangs are being allowed to act with impunity while victims are denied justice.
"The Government is effectively decriminalising car theft by letting these gangs get away with it.
“People across London want to know that if their car is stolen, the police catch the culprit. Yet instead, this Conservatives have decimated community policing, leaving victims of crime to fend for themselves."
The Lib Dem MP called for "a return to proper community policing".
Nationally, more than 100,000 vehicles were reported stolen without any culprit being identified in the 12 months to June.
The number of cars stolen in London topped 31,000 last year with the majority of the crimes unsolved.
Of the 31,017 vehicle crimes in the capital, no suspect was charged in 87.2 per cent of cases.
Scotland Yard has said fitting a steering lock can act as a deterrent to thieves.
The force added that any allegation of crime reported to the police "will be assessed to see if there are any viable lines of inquiry including forensic opportunities that can be progressed".
