IIRC, you can be cited for a DUI if you are sitting in the drivers side of a car that is not turned on.
Don't know if it still holds, but ages ago when I lived in Ohio (more than 30 years ago), they called it 'physical control of a motor vehicle while impaired' if you were in the car with the keys in the ignition (and stewed to the mickey...) whether the car was running or not.