The first set of PCB’s is ordered.
An adapter board to mount the XBee Wireless module and the arduino pro mini, including a small circuit to interface the shock sensor.
Second, an arduino shield to connect the XBee Wireless module to a standard arduino duemillanove board.
Well my car is not the newest – so I still need to open it by key or a remote with buttons. But the buttons of the remote are almost gone. the door lock is not soo god anymore, in winter it freezes sometimes.
Now I will try to build a motion-activated small arduino-xbee based remote. which still should be cheaper than buying a new remote 
And as I got infected by the microcontroller virus over 10 years ago by playing around with Siemens 80C537 controllers – I have to build it by myself…
planned is to use
- arduino mini pro (ATmega 328P)
- xbee
- self-built adapter board (like a shield)
- motion detecor (either a SCA-3000 – with 27chf quite expensive – or a mechanicel one, see distrelec.ch part number 647393)
stay tuned, more will follow…