A report by the Public Accounts Committee found that five percent of all road users avoided paying the Vehicle Excise Duty (VED) in 2006, up from 3.6 percent the year before, at a cost to the taxpayer of 214 million pounds.
Among motorcyclists that figure soared to 38 percent, an increase of 8 percent from 2005.
The DVLA (Driver and Vehicle Licensing Agency) now admits it will not hit its target of reducing the overall evasion rate to 2.5 percent by December 2007, the report said.
"Motorists and motorcyclists who refuse to pay road tax are stealing from law-abiding taxpayers and unlicensed cars are often associated with other forms of crime," said committee chairman Edward Leigh.
"And yet the Department for Transport (DoT) and the DVLA are losing ground in their fight against VED evasion."
The MPs said the effectiveness of the current enforcement regime is questionable and called for tough new measures to target offenders.
They suggested that in future motorcyclists who dodge tax should have their bikes impounded and have penalty points put on their licenses.
Persistent offenders should also be targeted before their tax is due for renewal to reduce repeat offending.
"If the DVLA's motorcycle enforcement regime is not to be a complete laughing stock, then the Agency and the Department must make the most of new powers ... and strongly consider more severe measures," Leigh said.
"Large parts of the biking community are cocking a snook at the law."
