I've solved this.
Here's what I did. I put my keys in the electronic safe, along with my wallet. Without the keys, I can't get in the car. And when I open the safe to get the keys, the wallet is shouting at me to pick it up, "Oi! I'm here! Don't leave me behind!". Voila. How can I miss it?
Not once I've left it since. Hope I'm not speaking too soon.
Sorry again, not a post on something I fantasized. *wink*