General Motors unveiled a stunning ultraluxury concept, the Cadillac Sixteen, at the Detroit auto show last week. The muscular Sixteen is powered by a 13.6-liter V-6 engine giving 1,000hp and a remarkable fuel economy figure of 8.5km per liter. GM boss Rick Wagoner says no decision has been made about whether the Sixteen will go into production. But GM Vice President Bob Lutz said: "I think the car works." See stories, Page 23.