Drivers who fail to pay congestion charges in London could have their car destroyed in a crusher.
TfL has threatened to crush cars
Latest figures from Transport for London (TfL) show more than a third of the fines from the controversial charge have not been paid.
Cash from the fines is set to be used on improving transport in the capital - and TfL says they are owed £7.4m in uncollected fines.
Now the organisation is planning to get tough by threatening fine dodgers with having their cars clamped - or even thrown in a crusher.
Since the road toll scheme began on 17 February about 110,000 motorists have been paying the charge every week.
TfL has said 244,170 penalty tickets have been issued so far. Of those, 92,369 have been paid and a further 58,183 have gone to appeal.
But 92,618 remain unpaid - amounting to £7.4m uncollected.
TfL said it is chasing the outstanding fines and will bring in the tougher measures to make sure of recouping the cash.
But critics suggest this may be difficult as records at the Driver and Vehicle Licensing Agency (DVLA) are only 90% accurate.
Conservative mayoral candidate Steven Norris, who said he will scrap the congestion charge if he is elected, said: "I don't know if this is the killer for scheme but the reality is that with this level of problems with enforcement, there have to be serious question marks as to how viable the scheme is."
A spokesman for TfL said congestion charging is a success and that it will be able to track down the evaders.