The most accessible and effective means is to put information about the company on the surface of the car. The car spends a lot of time on the road, therefore it provides a high frequency of contact with the brand, product and services.
Being stack in a traffic jam on the street, advert on the car allows the brand to be communicated to potential customers on average every 1 minute, which is much more often than the average contact time with other media. Standing in a traffic jam, a person who stands behind you is practically forced to read the information on the car and in the end it should reach someone interested in your advertisement.
Crucial to add:
No need to rent out additional advertisement space..
Advertisement on your car has a positive influence on your company.