BMW's Mini division has hit on viral gold with a popular email campaign that lets users create personalized messages that can be emailed to their friends.

Interactive agency Firstborn designed the campaign. Visitors to Mini's site can design their own Mini, which then drives across the screen and spells out a personalized message in its tire tracks. Visitors can email these messages to friends, DMNews reports. When creating the message, users can choose from four models of Minis and customize the color and the hood of the car. The user then types the message to be drawn out in tire tracks in the message's link.

"We wanted to get people to share the site with their friends, and then get them to actually visit the site," said Michael Ferdman, owner and president of Firstborn, New York. "As opposed to putting the message in the email, in which they may go to the site, or they may not."

The recipient will receive an email with a link to Mini's site, where they will be able to read the message.