In Final Fantasy 15 Regalia upgrades are not necessarily essential - especially when you use fast travel or pick up the flying car upgrade in the later stages, or get to grips with your Chocobo to flee across the world - but will feel that way if you're a completionist.
To tick upgrades off the list, you'll have to pay visits to Cindy over at Hammerhead, who has a questline for upgrades to pimp your ride with improved fuel consumption, a higher top speed, and a set of headlights that will prevent daemon attacks when driving at night.
All Final Fantasy 15 Regalia upgrades from Cindy's questline
The Ever Regal Regalia
Recommended level: 7
Kick the quests off by interacting with the metal bar near the gas pumps in Hammerhead. Cindy will ask you to fetch a pot of wax, so head for the marker and make your way into the tunnel. There will be a small pocket of Goblins in there, and the wax is lying in a pile of rubble about half way down the tunnel. Take it back to Cindy to complete the quest.
The Ever Elegant Regalia
Recommended level: 8
Talk to Cindy again; this time she wants a Redstone Shard to create some paint jobs - this is a non-unique item so there's a good chance you'll already have some by now in which case you can just hand it over, but if not then collect it from the marked area then head back to her to unlock some new decorations for the car.
The Ever Gleaming Regalia
Recommended level: 10
Head for Astor Slough and work your way down the hill to the marker. The fibreglass is tucked on the floor by the rusty car next to the large shack, so grab it and return to Cindy to upgrade your fuel efficiency.
The Ever Valorous Regalia
Recommended level: 26
Talk to Cindy again and then head to the Vesperpool. The Supercharger is guarded by a group of Cockatrices, vulnerable to Broadswords, Mechanisms, and Fire. Wipe them out and then collect the Supercharger from next to the rusty car in the middle of the search area and return to Cindy to upgrade your top speed.
Need more help? Our Final Fantasy 15 guide and walkthrough can provide tips on the open-world's many quests and activities. Learning how to get AP fast, EXP fast and Gil fast in Final Fantasy 15 will aid you in the many optional dungeons and tombs - including how to open and explore their locked doors. And if you want to get around easier, you can rent a Chocobo, learn the infinite sprint trick and later in the game, get the flying car Regalia Type F. There's also more to see and do with DLC, such as with Timed Quests.
The Ever Illustrious Regalia
Recommended level: 45
Talk to Cindy once more, and then head to Crestholm Channels. Click that link for our walkthrough of the area which show where to find the daemon-dispelling headlights, then return to Cindy to upgrade your headlights.