The phrase "optional sunroof" means that the sunroof is not included automatically with the vehicle, but can be chosen and added if the buyer wants it.
Sentences with «optional sunroof»
In 2003, the formerly optional sunroof and in - dash CD changer became standard. (automotive.com)
I purchased the Elantra SE with optional sunroof and heated seats. (edmunds.com)
An ST3 stickers for $ 29,825 with the optional sunroof. (automobilemag.com)