I have had my tools stolen from my unlocked car (VOLVO v70 2002) 4 times now. I know and fully accept it's my fault, but I'm just a dingbat!!

I've had this madcap idea that I could possibly use NFC or bluetooth link into the car's central locking to cause it to lock automatically when I move away from it.

Whilst I've built many things in my time, including recently using low cost Chinese bluetooth boards to add bluetooth to my formal stereo system, I'll admit I've no idea about how NFC works of if what I want can be achieved so really would appreciate some help and guidance on this.

Many thanks in advance

 

From you post, it seems that you want your car to know when you are nearby and be unlocked and to lock things up when you step away.

NFC is usually restricted to a few cm, so it is probably not suitable for your use.

There are some inexpensive and easy-to-use RF remote control modules on eBay and similar sites such as the one in the link below.
AU$1.00 432 MHz Remote Control Kit
It should be possible to limit the range to a few meters by merely using poor antennas or no antennas at all.

A system using these 432 MHz modules can be made inexpensively using "glue logic" (simple) integrated circuits and a few analog components. It might be just the right place for you to start.

Nordic nRF24L01+ modules are apparently repurposed (or once called "Failed") Bluetooth modules and they are inexpensive and very popular in the Arduino world. As far as I know in order to use them you need some sort of microcontroller to make them work. On the brighter side, you don't have to know much about programming if you start with an Arduino example such as that in the link below.
Arduino and nRF24L01 example

 

Thank you Dick. In the UK here 423mhz is allocated to OFCOM so mobile phone based stuff. With that being the case, I'd be loth to try it as I simply can't afford to have it not work reliably.

Hmm. The low power bluetooth would seem to fit. Is it true it only works for a few metres? I looked at the data sheet and ... Not got any idea I'm afraid of how to meld these things together ;-(

 

Doing this from scratch would take some programming and building. Some cars have this feature already. Have you thought about finding a retrofit kit or merely buy replacement pats to put something together. The one at the URL below uses RFID,
Keyless Push Button Start

 

Do you have the original keyfob for the central locking? if not why not use a separate kit like this...


http://m.ebay.co.uk/itm/433-92MHz-U...3Ae1c9ccf11590a357cdada072ffaacd2f%7Ciid%3A14