Funny you should mention this....
Once upon a time I had just this thing at the
knightmare. I had sacrificed both a spare OEM keyfob starter from a GM car, and one from an aftermarket company (
bulldog security) and hacked the "start" button to a um506. Even had these on week-day timers in the winter and enjoyed warm cars in the morning.
Even tried it with
BVC (lasted for about a week).
The advantages of this system was that the cars would automatically shut off after 15 mins if you did not get in and turn the key on.
These systems went out of service here after the wife started complaining of the price of fuel used and the fact that the kids thought it was funny to start the cars via the computer on any whim to impress visiting lady friends.
I still think this is a very good idea and would love to have it again, but alas, the hen rules the rooster.
Thanks for jogging my memory, and allowing me to relive one of my "failures". If you have any questions, I'd be honored to help.