I would look into Clifford alarms... They have a very cool accessory/feature that might be what you want. It is called BlackJax.
Basically you install a little 2 button keypad in the car and evertime you get in the car you have to enter your code.
It sounds annoying but it really gets to be second nature. I had this in my mustang for 3 years and I think I am going to have it in my runner soon as well.
The Keypad is very small (
see picture) and the way it works is simple. The top button is the number button and the bottom is the enter button. Say your code is 3, 4. You would hit the top button 3 times, then the bottom for enter, then you would hit the top button 4 times then the borrom for enter. The alarm would then chirp verifying the code was accepted.
You have 3 chances to enter the code properly, and if you don't get it right you have to wait 5-10 seconds to try again. this prevents someone from trying to get in your car and start punching until they figure it out.
How the blackjax works:
Each time you open the door (actually to be specific it's everytime the dome light comes on) the blackjax engages/resets.
Once you depress the break the timer starts. You have 30 seconds to enter your code, if you forget to enter it the alarm chirps and flashes the lights to remind you to punch the code.
If you don't punch the code in within 30 seconds the car shuts down and starts blaring the alarm. However if you are driving down the highway at night and turn your dome light on, then off and forget to enter the code the car won't shut down until you are under 15 mph or so. So you have no fear of getting rear ended at high speeds.
