We own '08, and '12 XC70s - 3.2 both.

We bought the '12 new, and the '08 used as it is the first year with the same body. Interestingly, the '12 is front wheel drive (many people did not know about this version) base model that we got for 26K new! It was poor in the snow, but far better with 4 snow tires.

I measured our 855R, XC60, and XC70 - they are nearly the same in the cargo area!

Do you need length or height? I think the 90 is shorter but higher.

If you carry stuff, get Volvo's rear seat net - its clever design can be used with the rear seat up or down, and the later version can be swapped between our "08 or '12.

As for power, neither car compares with our 855R - but both 3.2s are much better than our NA 850s which just seemed to make noise but no real power compared to the 855R.