A few years ago two guys took some mentos and drop it in some coke. The result was an "explosion" and they tried out a few different experiments with dropping mentos into coke. Well, these two guys are back, and have created car powered by Diet Coke and Mentos. They managed to travel 72 meters with the energy created by the "explosion" from droppping mentos into cok. Which, if you think about it, is actually rather impressive!
Here is a video of the car in action: