There are many special achievements in "Test Drive Unlimited: Crown of the Sun". The achievement of beautiful car body is one of the simpler ones. The way to complete the achievement is to customize the uniform. This can be done by going to any workshop on the island and then approaching you. For your car, go to Appearance Modification > Then use special spray paint to complete the modification.
How to make the Sun Crown body aesthetic achievement by unlimited test drive
Beautiful car body - create custom paint
This can be done by going to any workshop on the island, approaching your car, and going to the Exterior Modification > Paint section. You can create a Livery here and save it without applying it to your car to unlock this achievement (unless you want to spend 30000 points)
This can be done by heading over to any Workshop located on the island, approach your car then head to the Cosmetic > Liveries section. You can create a Livery here and save it without applying it to your car for this achievement to unlock (Unless you want to spend 30,000 Credits)
