Sorry, i have a Computer Science background so i'm bit weak in electronics.
It was a university project and resources were limited. By automation I did was to start the car from an android smartphone, unlock and lock the car. All the door locks were removed from the car and only smartphone had access to the car with an option of password which was embedded in the Hardware (arduino MC) in the car. Key was only used to unlock the steering lock but ignition switch and everything was disconnected from the ignition switch.
Overall system was acting as relay and we defended it by saying ?no one has time to bypass a Hidden Microcontroller inside a car?.
It had few snatching scenarios solutions, like if door is opened and ignition is on and you don?t give a secret signal from the smartphone, engine will turn off the ignition and then it will be started again by giving a password from smartphone application.
We only did for the sake of university project, a lot more things can be done like turning on lights, AC, monitoring car through GSM/GPS and with all this snatching solutions.
