NCR first approached Market Location last year after experiencing problems with the quality of its data and difficulties in securing accurate targeting lists from data suppliers.
Market Location was able to improve the accuracy of NCR's customer and prospect files by comparing the hire car-hire firm's database with its own, which contains information on 2.3m businesses.
The data specialist also analysed NCR's customer data to improve the effectiveness of direct marketing activity.
Market Location will now provide NCR and Guy Salmon with data services on an ongoing basis.
Nigel Bennett, Market Location's sales director, said: "We are delighted that the trial has proven to be so successful. We implemented a data strategy that was tailored specifically to National's needs and it has succeeded in unlocking powerful insight from their data."
Frank Reynolds, NCR's corporate marketing manager, said: "Market Location was the obvious partner for our b2b data strategy. They demonstrated an instinctual understanding of our business and data needs. [Market Location's analytics tool] Horizon in particular has proven to be extremely powerful, allowing us to take control of our data and targeting in a way that has not been possible until now."