Actually, the word is "to become" the world's most efficient country. Environment Minister Sigmar Gabriel unveiled very ambitious targets that would make Germany the most energy-efficient country in the near future. He said:

"We have all witnessed the dangers of climate change in the last few months. We only saw winter in the calendar in Germany. We should set ourselves the goal of making Germany the most energy-efficient country in the world."

I do not think it is impossible for them to achieve this; after all, this country has lead in the use of many renewable resources such as solar and wind. They have achieved and even surpassed their emission targets and with such a forward-looking perspective, they could very well be the country that we would pattern our energy programs after. Read more here.