sense when the car has started.

I have a laptop, a programmable relay controller for the laptop, and a cellphone I am using as a modem. My goal is to be able to call my laptop and start my car from anywhere in the world. My reason for this is so that I can start my car from inside a manufacturing plant 10 minutes before I leave work so its nice and toasty when I get outside. Other things I might use it for is to post the cars temperature, miles, speed, number of occupants, and any other info I can think of to a personal website. More or less I want to do this for fun as a hobby, however I've hit a snag.

I can program the laptop to answer the phone and take commands, and send commands to the relay board to connect the ignition wires to start the car, thats not the problem. The problem is I don't know how to tell the computer when to stop trying to start the car.

How can I get the laptop to sense when the car has started and tell it to turn off the ignition. Normally, when turning the key, the person starting the car lets go of the key when the car has started and this stops the starter, however, I'm trying to do this from a distance when I can't hear or see the car and need to somehow detect when the car has started and stop trying to start it. And further more, if the car doesn't start in say 10 seconds, to stop trying so the battery doesn't go dead.

Can anybody help me figure out how to do this?

I actually haven't tried starting the car yet with the laptop, this is just a problem I figure I will face and want to design for it before I start. I would think that if I held the key in my car forever, it would stop when it started anyway, but I haven't tried this, any light at all on this topic would be much appreciated.

You would probably be better off using a Stand alone remote start module.  They have connections for the tach wire that tells the module that the car is started.  They are programmable for 1 2 or 3 pulses to activate,  I am sure it will be easy for you to achieve a suitable output from your laptop to accomidate the module.

Also they have safety features such as the car dies if someone applies the brakes to put car in gear.   Without this your car would be at risk.

Yeah ok, I didnt think of that. I'll run in town and pick one up, thanks for the reply.