This song seems to allude to Sheryl Crow's called-off engagement to champion cyclist Lance Armstrong. Crow refused to confirm this in an interview with Rolling Stone magazine saying: "All I can say is that I've been engaged 3 times. So I have a thing about diamonds!"
In Gary Numan's "Cars," the message is that cars lead to a mechanical society devoid of personal interaction. This didn't stop automakers from using it in commercials. Both Nissan and Oldsmobile have used it in ads.