For a new engine displacing more than three liters, the standard inline six produces unimpressive power. Acceleration to 60 mph takes eight seconds, according to Volvo, but it feels like more from the driver’s seat. Cruising the Las Vegas strip, the six-speed transmission banged off crisp shifts that made the most of the 3.2-liter engine’s low torque peak, but on the open road the standard S80 ran out of steam when asked to climb hills or pass trucks. The V8 is a much better choice, and not just because it comes with AWD and gets to 60 mph in 6.5 seconds. It sounds terrific, moves the S80 with authority at all times, and is better suited to flagship duty.