The following is from http://www.ign.com/wikis/final-fantasy-15
Level – 7
Reward – 150 XP & Aero Wax. (used to improve the Regalia’s performance)
The Ever Regal Regalia
To begin this mission, talk to Cindy at Hammerhead after completing Chapter 2: No Turning Back’s mission: The Power of Kings. She tells you of a rare car wax that was recently spotted nearby. She was going to retrieve the wax for you, but Noctis and the gang offer their help. After your conversation, head to the next marker on your map. When you arrive, head toward the cave’s entrance. Just as you enter, you will be ambushed by some goblins. They shouldn’t be too much trouble. Take them out. Then, continue forward. Proceed through the tunnel until you see the wax on the ground. Pick up the item and you will be ambushed once again by a larger group of goblins. Take them all down. Then, head back to Hammerhead to talk to Cindy. This will complete your quest.