When it was first installed it was extremely fuel efficient, the 2.2 is a much better engine in that regard. Actually when my reserve tank warning light was working, it would let you know when you were 20 or so miles from running out.
The best I ever did with a tank, one of the older Subarus I owned was over 500 miles. I also used "Platinum gasaver" which gives the engine a hit of platinum vapors and rhenium gas. Not supposed to work according to the experts but apparently did!