I have watched the video and have had the pleasure of using a car with a similar system.
it was not a glamorous Mercedes but a Nissan micra - but the system was pretty much the same.
I too would like to make a similar system. Im not willing to compromise on anything - I want all the features - don't let people turn you off with stories of your car being stolen.
Sadly I only know the bear basics of electronics so that's no help. I will have to buy must of the stuff ready made and piece it together. But still will need some help on some things.
Ok the first part is you need a transponder. I have found one that will outclass the Mercedes and Nissan version. With the Nissan version u approached the car - u then pressed a button on the door handle, if u had the transponder in your pocket it would unlock the doors.
http://www.12voltshop.com/proddetail.asp?prodid=RFKE-22&cat=19&path=1,19
This transponder I have found will unlock the doors automatically when you are near the car door - so its hands free! (U can set the distance it will trigger - or u can also have it manual and press a button on the transponder).
If you move away from the car it will lock the doors. No intervention is needed.
Now my car has an immobiliser. I will also have to buy an immobiliser by-pass kit.
When the transponder is in range it will unlock the doors - there must be a wire on the receiver unit that goes +ve when in range and that goes 0v when the transponder is out of range. I will use that to signal my by-pass to mobilise/immobilise my car.
Also when the transponder is in range I will make it activate a relay that will turn the ignition on.
So far - when the transponder is in range I have
1. Open Doors
2. Immobiliser Off
3. Ignition On.
Those are all the ingredients U need to start the car.
But how to start the car (activate car starter motor)?
A crude way would be to have a switch to the starter motor. U would have to hold your finger down till the engine fired up then let go. If you did not hold your finger down long enough the car would not start. If you held your finger down for too long that would not be healthy. If the car was running and U pressed the button that would be worse.
What U need to do is hook up your starter switch to some electronics to give it some brains. So all u have to is press the switch. Your electronics would then determine how long the starter should be on for. If its a cold day the starter will have to be on longer for the engine to start.
If you held your finger on the start button the electronics would not keep the starter motor going.
Also if you added some electronic trickery U can have the same starter button turn the car off.
Unfortunately I dont know any electronics (yet) -
I have a remote car warmer and it has a wire that goes to some tach wire and that works well, it knows when the car is on and stops the starter motor.
Please can someone with some electronics know-how tell us how to build this intelligent starter switch. How do we know when the car has started so it cuts the current to the starter motor. Or is there a ready made kit somewhere (not that thats any fun - it nice to learn some electronics)
As for security I have never been concerned about it. Although I once had my stereo stolen.
The transponder is not in range - so doors are locked and immobiliser is On and ignition is OFF.
They smash the window and get in - still immobiliser is ON ignition is OFF - even with a stupid switch with no electronics behind it all they could do is turn the starter over - big deal.
Granted if they pulled all the panelling off the car located my by-pass kit and sent a 12v current down the right wire they could start the car. - what are the chances?