Hyundai is making a statement with their new vehicle, the Hyundai Tucson FCEV. And that statement is, "give us your poop, we'll fuel your vehicle".
So, they're not exactly asking you to bag it yourself, what they're saying is that they can treat sewage, let it emit gasses, and then use those gasses (hydrogen to be exact) to fuel their new car.
The good news is that everyone poops so we have plenty of that matter on-hand. The bad news is that there aren't many hydrogen fueling stations around. Oh...and have you looked at the price of a hydrogen-powered car?
Read the story on Hyundai's car here.