I have a Toyota Hybrid Camry with keyless ignition. If open the door (after I park the car) but before I shut off the engine the car will beep at me. This will continue until I get out and close the door. I have no idea what this feature is trying to tell me but it is very annoying.
As a side note I also recently rented a Nissan Maxima and this car does the same thing. Is there an easy way to disable this without pulling out wires?