The new Motor Vehicle Orders initiative will allow action to be taken against those who have sufficient financial means to contribute towards their own legal aid costs, but have then failed to make the payments owed, the Ministry of Justice said.
Under the scheme, which starts today, the Legal Aid Agency (LAA) will be able to clamp vehicles identified as belonging to the defendant.
After conviction, the LAA can then go back to court for permission to sell the car, putting money raised towards unpaid legal aid costs.
Justice Secretary Chris Grayling said: "Convicted criminals have cheated innocent taxpayers for too long by dodging requirements to contribute to the legal costs of their defence. I am determined that where they can pay, they will pay.
"Legal aid is not free - it is taxpayers' money. We must bring down the cost of legal aid and our starting point has to be that law-abiding citizens don't foot the bill when those concerned could pay themselves.
The scheme launches as Mr Grayling pushes through a raft of controversial reforms in his ''transforming legal aid'' consultation in a bid to save £220 million a year.
The Justice Secretary has previously denied that innocent defendants will be coerced into pleading guilty as a result of changes.
He said told MPs he did not accept that plans to pay lawyers the same fee for a not guilty plea as they would be paid for a guilty plea - which typically takes up less of their time - would lead to undue influence to plead.
And he denied performing a ''U-turn'' over plans to remove a client's right to choose a solicitor after he announced his intention to rework the proposal.
After consulting with the Law Society, which represents some 130,000 solicitors in England and Wales, Mr Grayling said he would look again at the issue and expected to allow a choice of solicitors for clients.
The Crown Court legal aid bill tops £700 million a year but only around 20% of the amount that should be paid back is currently recovered, the MoJ said.
All defendants at the Crown Court are granted legal aid for the cost of their defence, but are expected to contribute to some or all of the costs if convicted, depending on their earnings and assets.
Criminals have avoided repaying by refusing to cooperate with attempts to assess their income or the value of any financial assets they may have, or hiding income or assets to appear unable to pay.
New measures introduced in April mean that if an individual is believed to have assets but is refusing to provide the financial information needed to assess their contribution, they will be actively pursued for their entirety of their bill.