"A fuel-efficient, compact spacecraft has made it into lunar orbit, signaling Europe's first successful mission to the moon and putting the inexpensive probe on course to study the lunar surface, officials said Tuesday."

http://news.yahoo.com/news?tmpl=story&u=/ap/20041116/ap_on_sc/europe_moon_mission_4

"The spacecraft used only 130 pounds of the 181 pounds of xenon fuel it had aboard, according to European Space Agency spokesman Franco Bonacina in Paris. That translates to more than 5 million miles per gallon."

Yay, Ion Drive!