Flying Car Secrets in Final Fantasy XV

You have to load chapter 15 (after finishing the game).

Go to any sleeping area and call Umbra.

Select travel to past Lucis.

And go to your car in Lucis.

You need to auto travel to map point: Prarie outpost.

Run towards red fence in background.

And then wait for Formouth Garrison sidequest.

Note sidequest added to map.

After that, you have to get closer to the red fence.

Set sidequest to Formouth Garrison.

Go to location mark and start sidequest.

At this point, you need to kill all enemies.

And kill the last boss to get strange engine.

Sidequest into unknown frontiers added.

Now you will need to return to car.

Imperial bases gave 3 different car parts.

Formouth Garrison gave strange engine.

You could have done this base in Ch 8.

Aracheole Stronghlold gave warped wings in Ch 5.

For Vaullerey gave unstable stabilizer in Ch 6.

Killing boss automatically put parts in inventory.

After that, go back to Clindy in hammerhead.

And get Clindy to install parts.

Your car is now regalia type-F.

You need to ask Cilndy to customize your car.

Admire your car in 360 degree view.

Enter car and drive manually.

You need to honk horn in excitement (triangle button).

Press O button and fly into pole.

And then press O button near town to fly.

Enjoy unlimited fuel and fast air travel.

R1 button to change camera views.

Note: you can only fly within this Lucis Map.

To land, fly downwards close to a road.

Press X button when road is land-able.