making key copy?

[NoHeat]

My Cherokee key will open the door of my brother’s Arrow, but won’t start it or open the baggage door.

Any car key will open the door of the Cherokee I used to rent.

I learned this when I somehow got locked out of the plane, on the ramp at a distant airport. Another pilot overheard me describing my woes, and he suggested just trying ANY car key, since it's an old Piper. He said it will often work, and sure enough, it did!