L/100K per Car

Last day I was instructed to find out how much L/100K my parent's car used just to get me to school. Apparently, my car waste pretty much gasoline. Also, this is just for my parents drving me to school. My parents are busy people and are always on the road. I cant imagine Just how much is polluted and wasted.
We were also instructed to find out the L/100k of an energy efficient car. I was ashamed of my car when I found out about how much my car wasted compared to the energy efficient car. Now, imagine all the cars in the world doing the same or more than I do. My only comment is that this is not going to end well.

Apparently my car uses 16.8 L/100km and the nergy efficient cars use 7.8 L/100k. They use half as I do.
Also, I can see that oil sometimes is wasted like in the past year's oil spill. I do not consider this when I go into may car because I know that even if I get into my car or not, oil is still processed and might be spilled again. It would only be another incident in which I dont have authority of any kind.