Gas savers.

Running an engine leaner will save gas, but performance often suffers and often you'll just end up pressing harder on the gas pedal.

Run too lean, and the engine will run hotter, accelerating wear and tear on valves among other things.

My philosophy over the last few years, be as fuel efficient as possible focusing on regular maintenance (tire pressure, light synthetic oils, etc,), driving habits (easy on acceleration, avoid speeding, etc,) and keeping the car free of any unnecessary weight and unecessary drag (removed roof racks).

The "hyper miler" techniques are interesting, but my opinion, some of it is either too dangerous, such as "ridge riding" (riding over right edge of road with wheels on painted lines), or is merely trading fuel efficiency for wear and tear in other areas, such as coasting down hills in neutral often at excessive speeds. Such a habit may save gas, but the trade off is more severe wear on tires or brakes, not to mention how dangerous such practices can be.

I want to be fuel efficient, but not at the expense of spending the same or more money on vehicle wear and tear.

 

I've been paying extra attention to the condition of my Audi's complicated vacuum system. I found a very small leak several months ago that yielded +1-2mpg after it was repaired. I also started using 'LubroMoly Mos2 Anti-Friction Engine Treatment' which has made a noticeable difference in smoothness & driveability...but I shall NOT be so bold to attribute better FE because of it.

 

Not so.
This is a correct comparison between GM cars using the 2bbl Rochester vs. the "spread bore" Quadrajet 4 bbl. but doesn't apply universally.
The 2bbl Rochester has venturis way larger than the primaries of the Q-jet, so given a light throttle foot(stay out of the secondaries) the Q-jet will be more economical. "spread bores" is the term used for primaries smaller than the secondaries. Carter(Thermoquad) and Holley later adopted the concept.
Jetting any carb down has other effects not always desireable, especially with the awful "gasoline" sold these days.
A conversion from the 2GC Rochesters to a Q-jet is win/win.

 

My Colony Park is my gas saver. The Caprice's 4 barrel dumps gas like it's going out of style, and my Silverado gets 14-17 on a good day.

 

One of the biggest things is the tires. Some roll, some seem like driving with the brakes on! Unfortunately, not a wagon, but perfectly honest comparison:

92 Crown Vic, 4.6l V-8. It had Daytona tires when I bought it. The damned thing was managing 250 kms a tank around the city. Upped the tire pressure to the max of 44, and managed 300 kms. Switched to the Pirelli P3000, nd suddenly, 400 kms a tank. Both sets were P225/70R15. The Daytonas were S rated, and the Pirellis were H rated.

 

Here's a real gas saver. Install tires with a 1.7" larger diameter. Your speedo and odo will run 6% slower so when you do the math you'll think your getting 6% better gas mileage.

I just don't believe that a 70's two ton wagon can get 45 mpg. Sorry. Unless of course every trip is down hill.

 

That is amazing that you saw a 60% increase in mileage from simply changing tires.