Many cars have remote/key combo devices that are too large for this key pocket. My current key fob (Mini Cooper) is nearly 2 inches in diameter.
Here's what I do. I put my car key (fob in my case) on a small ring that fits on a bigger, quick release key ring that holds all my keys. I use the Nite Ize Locking S Biner now, but I've used a standard carabiner in the past.
I put a small, disk-shaped Neodymium magnet under the rear wheel well somewhere up high so the key cannot be seen when hung from it.
When I go to run, I take the car key ring off the main key ring and attach it to the magnet. It can't be seen by passersby. It's easy to get to, convenient, and I don't have to worry about losing the key.
Just to avoid reaching around under a muddy wheel well, I put a small dot on the chrome ring around the wheel well with a marker. That way, I know exactly where the key is.
I also keep a spare key in one of those key magnet holders under my car. About once every 2-3 years, I lock myself out of the car. Do this. It will eventually save you an hour or more waiting around for a locksmith to arrive. If your car has a key fob remote like mine, you can put the valet key in the key holder to avoid buying another remote.