The campaign will be geographically targeted to reach UK-based users who are looking at ten major cities on the mapping service.
National Car Rental has produced creative to match offers and locations to the city being searched by Multimap users.
Leaderboard adverts will be served on Multimap when people with UK IP addresses search for maps in ten cities including London, Manchester, Edinburgh, Belfast and Bristol.
"We want to do more targeted marketing in order to increase bookings in these destinations and have produced ten creative executions, one for each city. IP and geo-targeting on Multimap creates a powerful combination and enables us to maximise our online advertising budget," said Amy Dorrington, internet marketing manager at National Car Rental.
Jim Cruickshank, general manager, B2C at Multimap, added: ‘Many of our customers use Multimap when they are planning a journey and now they can benefit from discounted car hire. The ads are only served to people in the regions where National wants to increase uptake and meet our commitment to provide a range of rich and relevant local information for visitors to Multimap.'
To bolster the four-week Multimap activity, National Car Rental is also running search, affiliate and email marketing.