Spare hide-a-key for both access to the car and starting?

Question

My wife and I have a pair of Chevy Volts. Mine is the 2018 model, hers is slightly older. Each came with a spare mechanical key in addition to the radio keys. The mechanical key can be used to open the doors. On her car, there is also a mechanism for starting the car using the mechanical key, but they seem to have eliminated that feature in my car. In mine, I think the idea is that if you suddenly realize that the radio signal is too weak to work, you get in the car using the mechanical key, but then put the radio key in a special compartment, presumably right near the antenna, where the signal strength is stronger.

I'm looking for a workaround for this problem. I go hiking and running sometimes in the mountains at trailheads where there is no cell phone reception, and I would like to be able to have a spare key hidden in a hide-a-key box so that if I lose my radio key, I can still get home.

The best idea I can think of is maybe to take the second radio key and wrap it in aluminum foil to act as a Faraday cage. If this works well enough to block the radio signal, then I can leave that key in the hide-a-key box. But even if that works, it's not a great solution, because it makes it inconvenient to use the second key in everyday life, e.g., I'm out walking the dogs and my wife needs to move my car.

I could buy a third radio key, but those are usually insanely overpriced.

Does my analysis of the situation make sense? Any ideas for a better solution to this problem?

Answer 1

My Subaru has push button start. If the car senses the key fob anywhere inside the car, I can not lock the doors. The fob has a mechanical key (#2 in pic below) that will open the driver's door. To lock my car with the fob inside, I put the fob without the mechanical key in a triple layer of tin foil inside a mint tin. After hiding that, out of sight, in the cabin, I manually lock the door (with the lock lever, not the button on the door) then close the door. The mechanical key stays on a lanyard around my neck. When I want to get back in, I use the mechanical key to open the door and open the tin and foil to start the car.