You may own a cool car you may even own a truly great car but it's a cinch that no matter how fantastic it is, it can never be anything more than the second best car in the solar system. The greatest of all is the Mars Curiosity rover, one ton of SUV-size machine now 160 million miles from Earth and trundling across the Martian surface. It was the rover's landing on Mars last August that first caught people's eyes: an improbable operation that required a hovering mother ship to lower the rover to the surface on cables like a $2.5 billion marionette. But it's the two years of exploration Curiosity has ahead of it with a suite of instruments 10 times as large as any ever carried to Mars before that will make real news. NASA built the country one sweet ride, and yes, alas, it's sweeter than yours.