Our garage has an incline, meaning with the parking brake disengaged, the car can roll out without any external force. My father takes advantages of this and rolls out of the garage often without the engine started while in neutral position, saving some gas according to him.
Today I wanted to take the car out for a wash, and attempted the same, as the weather is cold and doing so can save an unnecessary cold start. However, with the poor lighting condition in the garage, I accidentally put the car in drive and backed out without knowing. I realized this after I was outside. I backed out slowly and traveled only the length of the car. The car was never started during this.
My dad was unhappy upon hearing... even though my intention was good. I just want to know what are the consequences. It's a 3-speed AT Toyota corolla 98 (if it were a new car I'd be toasted)