Recently, Korean scientists created glow in the dark cats and scientists have created glow in the dark rabbits and pigs in the past. Glowing animals are novelties but GMO or Genetically Modified Organisms are actually quite common in our food supply and you often see these foods bannned because of concerns over safety. While not technically possible currently, the creation of genetically engineered vehicles is imagined in science fiction and fantasy (like the cat bus in the anime My Neighbor Totoro, which you can seen in the videos above and below the fold).
A living car would mean efficient production, repair, energy collection and disposal because living systems are much more efficient than traditional technologies. However, the impact on the eco-system is unknown and possibly detrimental. For example, a cat bus might escape, grow wild, change the eco-system and endanger the survival of some species. So, while it would be really cute and furry to ride in a giant cat bus, it's probably not a good idea to create these things until we have a much better idea of their impact on the environment.