Campaign revealed the pitch, which was managed through the AAR, in May.
The win means MediaVest will run offline and online media for the Ford dealer group, as well as mobile, experiential media, events and sponsorship activity.
Ford Retail operates 65 Ford dealerships in the UK, under local brand names including Dagenham Motors and Heartlands Ford.
It claims to be the world’s largest dedicated Ford dealer group and is planning "very significant changes" to its advertising, following the centralisation of its marketing function in an internal restructure.
The group previously worked with MB Advertising, which is thought to have been involved in the pitch.
MediaVest will report to Celia Pronto, marketing and ecommerce director for Ford Retail Group.
Pronto said: "We were looking for a media agency partner to help us make a step-change in the way our organisation goes to market. Our ambition is to be a world-class retailer, and in order to achieve this are looking to create a significant and noticeable shift in how we communicate."
The win does not affect Mindshare, which holds the main Ford media account.