I traded a 2009 XC70 3.2 AWD for a 2011 XC70 T6. The turbo engine significantly improves this vehicle: quieter, smoother, more than adequate acceleration and no noticeable reduction in mpg. The 3.2 is slow, buzzy/noisy and it gets lousy mpg (worst of all worlds).
You're always aware of the engine working at the limits of its capacity to move this heavy vehicle. And, while the T6's base price is $6k higher, it comes standard with AWD and premium/leather package which are nearly always added to the 3.2, so the "base" sticker price of the T6 and 3.2 are essentially the same before other options. Why not get the bigger engine?
Cargo capacity, rock solid build quality, seat comfort. We've had 3 Volvos in the family with no defects or service visits other than for free scheduled maintenance. While people may think of Volvo as floaty family barges, this vehicle handles well, doesn't lean in corners, and the suspension is nicely firm. It's not as nimble as the XC60, but it handles well enough for its size as long as you don't push it too hard. The direct injection turbo engine (300 hp, 325 lb ft torque) is worth the extra investment. I drive BMWs exclusively (the Volvo is the family vehicle) and even I'm impressed by the engine.
Xenon headlights should be standard on a luxury vehicle, not an $800 add-on. There's a little too much exterior plastic cladding. MPG is still in the range of last decade's SUVs and should be improved.