23 mpg city is nothing to sneeze at, it is really good. 29 mpg city is unheard of, even with FWD. A V70 with an NA engine can get around 30 mpg highway, depending on how full the wagon is and which way the wind is blowing.

Removing the prop shaft is common, and fairly easy to do. If you plan on re-installing it, remember to mark each section so that it can be put back as it was. You do not want an imbalanced prop shaft coming through the floor of the car or destroying the center baring or pinion seal. It is heavy...

If you remove the shaft, beware of a few things. Your car will torque steer. The slip control will no longer function as well. Driving in the rain can be a bit dicey, to say the least. Your mpg will get better.

Klaus
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There is no present time, just the past and future