Up to 55% of drivers in Wales admit to speeding on most days, according to a report published by the RAC.
The research claims the number of drivers speeding regularly is up almost 10% on a year ago.
It said that overall 57% of drivers broke the motorway speed limit, and almost two-thirds exceed 30mph speed limits.
The figures came as another survey showed Wales had one in eight of the UK's mobile speed camera sites.
The 2005 RAC Report on Motoring published on Monday suggested current enforcement of speeding restrictions appeared to have little impact.
The most common reason given for speeding by those surveyed was the small chance of being caught. The RAC has termed this "driving under the radar".