Ozone is O3. Oxygen we breath is O2. Ozone is less stable than regular O2 molecules, so it releases the extra oxygen that then bonds with other materials. For our purpose, it oxidizes anything organic living and/or smelling. Mold will not survive. Smell causing organic molecules will not survive either. It's similar to hydrogen peroxide, which is H2O2. Water is H20. The extra oxygen is released, which is why it is very effective at killing mold and removing any organic stains like blood and wine.
What you do is put a device in the car that converts the air into O3. The longer you leave it on, the higher the concentration of the ozone in the car. Essentially all of the air in the car will become toxic to mold and smelly substances. Because it is a gas, ozone's reach is much farther and thorough than you can get by hand. I suggest removing the carpet before running it since it's harder for the gas to get concentrated under the carpet. If you can't find someone with a machine (detail shop, tool rental company, cleaning company - they use them in hotel rooms to remove smoke smell), you can buy a cheap ozone generator for about $100-$200. I can recommend a cheap one we use via PM if you like.
You want to avoid breathing ozone as it can irritate your lungs. Hold your breath, start the machine, then close the door. I would run it for 1-2 hours depending on how bad the mold is. The key is getting the concentration up. A 2 hour sessions is much more potent than two 1 hour sessions. Once done, hold your breath, open a door and walk away leaving it to air out for about 15-30 minutes. It will smell a little like chlorine for about a day. After that it will smell like new. All of the old smell will be gone. To be safe, you may want to remove any light colored plastic trim in the car. I've only heard of ozone yellowing plastic but it's never happened in any of our vehicles. I'm sure it depends on the type of plastic .... It's really quite amazing how well it works though.