Police officers conducted raids in Leicestershire, London, Manchester, Thames Valley and the West Midlands early on Wednesday.
They have been investigating a practice known as ghost broking, which can leave young drivers uninsured.
Insurance companies say those responsible target drivers on a budget and looking for a cheap deal.
Fake cover warning Police say ghost brokers operate through websites, social media or small ads by offering cheap insurance.
They target young motorists who face high premiums and communities where English is not the first language and where there is a lack of understanding about the way the insurance industry works.
In some cases they issue completely fictitious policies.
In other cases they apply to genuine insurance companies for cover on the customer's behalf, but alter personal details such as age and address which would otherwise push up the cost.
Anyone with such a policy could end up with their vehicle seized by police and face fines.
In November 2011, the BBC revealed that 20,000 motorists could be driving around uninsured after buying fraudulent or fake cover.
The City of London Police's Insurance Fraud Enforcement Department (IFED) has been investigating the issue, culminating in operations involving 160 officers on Wednesday.