Ok, technically not free fuel but here's a thought. You drive wherever, get there, brake to a stop and A.) put the car in park and then turn off the engine or B.) turn off the engine and then put the car in park. B turns the car off 1.5 seconds sooner. Big deal. Times 1,000 times per year you turn off the car is 1,500 seconds per year which is 25 minutes additional run time. Obviously people have widely varying numbers of trips per year but it's still a savings every time.