RE: Gas mileage with an automatic
Okay.  My '90 GL Westy, stock 2.1L, heavy at well over 5,000 lbs (measured
on the scales), when in tune, gets 17.5-19mpg on the highway, cruising at
about 60 or below (maybe 65 in heavy freeway traffic).  I've had segments go
over 20 and and down to 16 for some road conditions.  But on a trip last
January I was only getting in the 15-17 mpg range.  When I pulled the plugs
they were way overdue for replacement.  With new plugs in (and timing
tweaked) I'm back to what I had been getting, the high 17s to 19+ mpg.
Now, for in city driving?  I haven't checked that recently but when I did, a
few years ago, it was in the 13-14 mpg range.
So my suggestions: Basic tune up, cap, rotor and plugs.  And plug wires,
check both ends for corrosion.  Then make sure timing is where it's supposed
to be.
One more thing.  When, for a couple of days on a four years ago, I had to
drive with the O2 sensor disconnected, I got about 13-14 mpg on that tank.
Not saying a bad O2 sensor just that that is what I got with the O2 sensor
unplugged.