I believe there is a legitimate reason for this button. If you are running on fumes, or are stuck in a traffic jam. Then it can reduce fuel consumption and even save your ass.

However..... DO NOT FUCKING TURN IT ON BY DEFAULT!!!!

Holy shit, I live in the mountains in the middle of bumsfuck nowhere. I do not need this feature enabled by default. You can give me that mother fucking button as an option sure. Keep it there with the 30 others that I have no idea what the fuck they do.