You'll search long and hard before you find the magical combination of fuel economy and interior space in your xBox.
For what you would pay for a new-to-you car, you could do a LOT of refurb work on your Box.
Another guy on this site,
Sentra SE-R who appears to have gone dark since about mid-2014, racked up thousands and thousands of miles with an '06 xB, and his lifetime average is nearly 49.5mpg. That's really, really good and possibly not matchable with current offerings.