The crackdown was carried out by CID officers drawn from various formations including the Flying Squad and Interpol officials.
Most of those impounded were top of the range vehicles suspected to have been imported irregularly into the country.
“We are detaining the vehicles to scrutinize them and see if any of them match the details given to us as having been stolen from countries abroad,” a police officer involved in the operation said.
“Owners or those found with them will be required to cooperate with us so that they can assist us understand how they got them because some of them are reported stolen elsewhere,” the detective added “but those found to have no problem will be released to the owners.”
Officials from the Kenya Revenue Authority (KRA) were also involved in the operation.
“This is an ongoing operation, it is not meant to harass anyone. It is a normal procedure,” Nairobi CID chief Nicholas Kamwende said.
Similar operations are underway in neighbouring Tanzania, Uganda and Rwanda among others.
Owners or drivers found with vehicles which raised suspicion were directed to produce original documents to enable the officers understand how they were imported into the country.
A similar operation conducted five years ago saw several vehicles detained, although others were released to owners much later.