Back when I began I set a totally baseless “goal” of 25mpg.

That would make my (CAFE exempt) 2.5-ton full-size commercial truck
more fuel efficient than the average passenger car on the road today.

The changes since I last posted:

-Replaced mechanical vacuum
pump with an electric one (from the wrecking yard – they don’t have a
list of cars, and most of the insignias have been pulled off, so I had
to check each one.  I found it in the very last row, after having gone
through probably 200 or so)  This allowed me to remove the alternator
belt altogether.

-Replaced belt driven radiator cooling fan with an electric one. 
It has a thermostat, so it only goes on when its actually needed.  It
also weighs about 1/10th as much, so it doesn’t require as much energy
to turn.

-Added an underbelly pan from the front bumper to around 1/2 back
to smooth out airflow beneath the vehicle, along with little spoilers
in front of the front tires (they were big spoilers at first, but they
rubbed the wheels at highway speeds and wore away) 

-Removed the windshield wipers to make it a little more
aerodynamic.  They, along with the alternator belt, live inside the cab
now just in case I need them unexpectedly.  They de/reattach with no
tools in just a couple seconds.

-Replaced the grill tape with a sheet of coroplast (same stuff the
belly pan is made from) so it can be removed easily in hot weather. The
engine runs better warm in general, but the new fan isn’t quite as
powerful, and between that, the grill blocking, and driving (faster
than usual, 65mph) in the hills during the brief hot weather we had
last week, it did overheat once, so I thought it better to make
something that could quickly and easily be removed and replaced later.

-Removed power steering pump and replaced steering gear with a manual steering gear.

I’ve also added a solar panel, changed my aux driving lights to 5w LEDs and moved them to inside the grill.

The average brand new passenger vehicle (inc. cars and light trucks) gets 26.7mpg.

On my last fill up my 1983 commercial truck got 26.85mpg