Have you completed the standard Hd campaign mode, and cleared every event with a medal?(type doesn't matter bronze/silver/gold)
If you have, you'll unlock the Chrome/sliver ship skin.
The "Bling Brigade Trophy" requires a group of 8 people, all race a single online race with every person using the Chrome/Silver ship skin. --- I've fought with this fellow here thousands of times. The speed we create together is beyond anything you could imagine. - Vash