The solar-powered prototypes will travel more than 800 miles (1,300 kilometers) through the world's driest desert in the four-day, multinational race.
There are two categories: cars powered only by solar energy, and three-wheeled models that get a little help from pedals pushed by the drivers themselves.
The cars had to be built for less than $7,000, forcing their makers to be creative more than wealthy. Most of the teams represent university engineering departments.
The big finish comes Monday, and the winners get prizes of $30,000 in the solar category and $9,000 in the hybrid category.