Ok, this may have been discussed before or even done, but I couldn't find it. I was thinking the other day that it would be really awesome if instead of stevieg's access control I made something that demanded a password "ignition code" and if it didn't get it within 30 seconds it would kill the fuel pump or injector electrical circuit or something necessary but not crippling to the handling of the vehicle so that they wouldn't crash... just not be able to get away. You could have it either ask for it imediately or delay 10 seconds or something.. but then progressively get more emphatic and warn of vehicle disabling at the expiry time.
It would require a simple application that I could code with a few helps from people on board here that have better coding skill than I (or would want to do it for me :D ) , a usb i/o interface... phidget or vellman ect. with atleast 2 digital outs, and a latching relay. The application would send a pulse to the relay which would effectively switch the power off to the pump... it will remain off until thrown back... this would keep crafty theves (whom at this point probably are running cause they are still too close to the crime scene and won't want to pop the hood for a better look) from shutting the car off... wating for the pc to go off then starting it again and making it farther... or ripping the pc out so that it won't hold the relay open. The other "optional" but really recommended item would be a bypass... we love our computers, but lets face it... they are untrustworthy at best. I would go with either a hidden switch or, my preference... a key switch in the glove box... you would have to open the glove box and insert a key ( which I would keep in my wallet or locked in the trunk or something seperate from the key ring) to get it to run again.
The software could be really indepth or simple... but you could add like service mode which would allow a simple code to access it for limited time, or just limited time with countdown on screen letting them know that they better not try any crap. A limited number of tries... logging... different passwords for family members (lol, not usefull for me :( ) shutdown after a period of time after code failure... so that if they run the battery doesn't crap out with the key on...
I'm sure there are bugs, but it seems like a great idea, and given my poor creativity skills... I figure somebody must have atleast thought of this... but I couldn't find anything in searches... there has to be some obvious problem I'm overlooking