A team of engineers at Åbo Akademi University have devised a way to race two Lego cars at speeds up to 40 km/h (25MPH). The secret sauce that produces this speed is our old friend diet coke and mentos.
The researchers created a machine called the CoMet Machine that houses the Diet Coke (or in this case Coca Cola Light) and mentos. The explosive reaction causes a spool of fishing line to spin. At the other end of the fishing line is the Lego car which is pulled towards the CoMet at breakneck speeds.
This experiment is great for the weekend DIY warrior. Not only does it combine Diet Coke, Mentos, Legos and speed, but the best part is that it's easy enough for you to duplicate at home. [Technabob]