The website also logs reports of good driving
A website which publishes registration plates of "bad drivers" could lead to vigilantism, police have said.
The site's founder Andrew McGavin, from Chipping Norton, Oxfordshire, said more than 11,000 reports of alleged road offences have been logged.
He claimed the problem of bad drivers was not being taken seriously by the government. He added drivers appearing on the site can contest any complaint.
But police said people should report road offences to local officers.
Mr McGavin, who has been running the site for more than a year, said: "I built the website because people told me not enough was being done by police about speeding and dangerous driving.
"People will drive at 40mph in a 30mph zone, that extra speed would kill a child if they were hit.
"The site has seen more than 11,000 reports, including more than 2,000 'mobile phone drivers'.
"But any driver highlighted for poor driving can explain, they can put a comment on a number plate, they could put a green report on their own vehicle or send an email saying 'I don't think this is right'.
"The website is an embarrassment to the police, in a way it is naming and shaming them to get more done."
In a statement Thames Valley Police said: "We sympathise with the concerns that people have about poor driving in their local areas.
"But we do not condone this type of website because we are concerned it may lead to vigilantism.
"We would recommend that people contact their neighbourhood policing team about any concerns they may have about poor driving in their area."
Mr McGavin said he had no intention of shutting down the website.