2010 Jaguar XJ Spied Testing New Engines In CoventryThe 2010 Jaguar XJ is nearing production and its makers are pulling the stops out to finalize its new engines. The new XJ will debut three new powerplants that should deliver both improved performance and improved efficiency. And boy does the Jaguar range need plenty of both. But what will they be? A 5.0-liter V8 available in both supercharged and naturally aspirated form will power the range topping XJ V8 and XJR. Expect more power than the current 4.2-liter V8, which makes 300 HP and 420 HP with the aid of a blower. A 3.0-liter straight-six, equipped with some kind of forced induction, will match the performance of the current naturally aspirated V8 while delivering better fuel economy. Expect 300 HP and nearly as much torque. There will also be a heavily revised twin-turbo 2.7-liter V6 diesel that should deliver more than the current engine's 207 HP and 321 lb-ft of torque. Expect increased economy and reduced emissions as well. [via Car Magazine]