Thermal efficiency is how much of the potential heat energy of the fuel used is actually returned as work at the wheels.

FORBES: How to Build a Car that Gets 54.5 MPG

"Our potential in thermal solar power is four times the world's energy consumption, so you can have all the ambitions you want with that, " Tewfik Hasni, managing director of New Energy Algeria, or NEAL, a company created by the Algerian government in 2002 to develop renewable energy, told the Associated Press last year.

FORBES: Magazine Article