yeah that would be a great idea. my bro in laws toyota does this ffs! I reckon it would be hard to retro fit, but not impossible. surely there is some module somewhere that activates when a linked device is in range. if it could be installed in line from the ignition to the ecu, then the igniton barrel removed from its original position and hidden under the dash somewhere with the original key in and ON. when you have the trigger device on you and approach the car, it would activate and connect the hidden ignition barrel with key in(already on) and the car would get ready to start (prime fuel pump, all dash check lights on). then all you would need to do is push the starter button and your away. there would be some bugs I can think of straight away, like how do you turn the car off? this could be done by replacing the original start button with one from a car that starts AND stops the engine, or prol easier with a second button that would momentarily cut power to the module to kill the engine. however in that case, when you release the stop button, the ignition would come back on, ready to start the engine again, which could be annoying.... of course, that would all turn off when you walk away.... then theres the task of the car locking/ unlocking when you are in/ out of range....