Guys, the wave of the future, NO KEY. My wife bought a Mazda RX-8, no key is needed, just a credit card sized hunk of plastic with a chip and battery inside. Slip this little card in your hip pocket as you leave the house. Walk up to the car, the car will scan and read the chip. Push a little button in the door handle and the door unlocks. Unless the card is present to be read the door will not unlock.
Get into the car and just turn a switch, the car starts, no key needed, just a reading from the card in your pocket. Get out and leave the car running, walk away the car will continue to sit there and run. As soon as someone tries to put the car into gear the engine shuts off, and will not restart till the security card is present. Someone wants to car jack the vehicle, get out let them have it, run. As soon as they go 15 feet from the security card the engine will shut down, and not restart till the security card is present.
When the wife and I go shopping and park the car when I walk 15ft from the car it automatically locks. When I return, the car recognizes the security card in my pocket and unlocks when I push the button on the door handle. During cold weather if I leave the car running, again it locks when I get 15 ft from it. In the event some one should break a window and get inside. As soon as they push the clutch the engine shuts off.
In the event of a dead battery, and the security system is down, there is a key embedded in the card that can be removed and the cover over the ignition switch can be removed to start the car with the key while jumping. That little key cost $76.00 at a Mazda Dealer, the only place to get one. Then it cost $100.00 to have it programed to match the security system in the car. The reason I know, when on my road trip with my old high school buddy I lost one of the keys somewhere in North Carolina.