Dyfed Powys Police are urging people to check their vehicle insurer is registered with the Motor Insurance Bureau.
The force has a right under section 165 to seize vehicles which do not have insurance.
The way officers check if a motorist has insurance is by checking systems which gets the information from the MIB database.
Chief Inspector Steve Matchett., Roads Policing Unit, said: "The MIB database is used on the road side to see if someone has insurance.
"If the company is not registered, your vehicle is likely to be seized as we cannot allow an uninsured vehicle on the road.
"We are urging people to check their car insurer is registered to save them the inconvenience and cost of having their vehicle seized."
Motorists can check if there vehicle is registered by logging onto http://www.askmid.com">www.askmid.com
CI Matchett added: "There is no way round the database for people who are genuinely uninsured.
"Driving without insurance is not only an offence but it can impact on other people who are using the road lawfully. We will be carrying out stop checks throughout the force in a bid to clamp down on those who flout the law."