"Optional navigation" refers to a type of choice or decision about whether or not to utilize a system or method of finding directions or routes to a destination. Full definition
Whether you're taking a family vacation or traveling for business, your vehicle's optional navigation system will help you arrive more easily at any destination. (toyota-en-us.visteoninfotainment.com)
This is all thanks to the latest sound systems, along with an available infotainment system with optional navigation that can make the ride more fun! (ontariovolkswagen.com)
Lastly, a 7 - inch color display with a central controller on the console gives you convenient control of audio, video, hands - free calling and optional navigation functions. (mbseattle.com)