New reports from the Department for Transport reveal that the number of people not paying their road tax is increasing in line with the number who drive without cheap car insurance.
For the first time, annual road tax evasion rates topped two million in 2006, up from approximately 1.5 million in 2005.
The rise in non-payment comes in spite of a high-profile public awareness campaign run by the DVLA, which warns road tax evaders to expect prosecution and hefty fines.
In terms of vehicles, the report showed there were 1.3 million untaxed cars and vans on UK roads in 2006, which left the government with a £170 million revenue deficit. The average road tax on these vehicles was just £127 - substantially less than the price of even cheap car insurance policies.
"If 2 million people are prepared to risk fines and jail time over a £127 tax, what chance do the car insurance companies have?" said Mike Page, spokesman for the young driver car insurance specialists at Hoot.
"There's no way a driver who baulks at the price of road tax is going to fork out £900 for the average motor insurance quote," he added.