The 8-year-old design of the P180 Avanti from Italy’s Piaggio Aero (www.piaggioaero.com)—a turboprop with an unconventional appearance, roomy interior, and superior fuel efficiency—has been upgraded. The Piaggio Avanti II displays the same unique exterior, with its aft wing that holds two rearward-facing engines. This configuration provides an unusual amount of lift, reducing drag and cutting fuel requirements by about 30 percent compared to light jets. The new iteration has more durable Pratt & Whitney engines, but the most significant advances appear in the interior, where the seating is more comfortable and analog dials have made way for a digital Collins Pro Line avionics system with three flat-screen displays. The nine-passenger Avanti II has a range of about 1,735 miles, reaches a maximum speed of about 458 mph, and is priced at about $6.5 million. . . .