When attaching stuff to keyrings, etc., I like to use Photon's spring clips. They are small but stout, and the spring is plenty strong, far stronger than the notorious Nite-Ize S-clip (a.k.a. the "Shur-Looz"), for example.

And if you use those to attach your car key to your overloaded keychain, you just unclip it from the rest of the overloaded keychain to save the ignition switch. I do something similar to this with a large carabiner. Keys slide on the carabiner via split ring attached to the key; simply remove the key needed and the rest stay clipped to the belt loop. FWIW and YMMV.

Thanks Jeff, I just lost a ring of keys using those Nite-Ize S-clips and pulled all those clips out of circulation. I ordered some of those clips from Photon in Silver and Black and they are very nice indeed, thanks for the info and link.

Try this, take your vehicle ignition key, hold the metal cut part in your index finger and thumb to resemble it in the ignition switch,and let the accessories dangle and think about the tiny tumblers in your vehicles ignition switch. Too much weight can prematurely wear the cylinders. There are not any test procedures during the switch designing phase that I am aware of for maximum load. Also be aware of any magnetized metals close to the transponder in the ignition column and in the key itself. A strong emf could erase or reset the code, and not allow the vehicle to start. Looking at your ring, I would say you are probably maxed out. I guess you are close to a 1/2 lb.?