Uninsured drivers are adding an average 25-30 to the premium of each insured driver, according to the latest Government figures.
Estimates suggest 1.5 million motorists didn't hold valid insurance at some point during the past 12 months the equivalent of one driver in 15.
The figures also show there were 392,763 court cases against uninsured drivers in 2005, the most recent year for which figures are available.
However, campaigners say the punishments handed down by courts are too lenient. In particular, protestors want all uninsured drivers who kill to receive jail sentences.
At present, even repeat insurance offenders can avoid prison under sentencing guidelines and the average fine for uninsured driving is 177, while the average cost of comprehensive insurance is 800, according to the AA.