Not that I'm complaining . . .

Anyone know why my fuel consumption would suddenly go from years of 26 mpg
to about 33 mpg? It started about two weeks ago, with the only new
occurrence being a change from Sunoco gas to Citgo. I can imagine there
being some minor difference between the two stations, but enough for a

engine operation would be affected?

FWIW, '98 SL2, 68K mi, located in Central New York, most trips <7 mi, new
ignition control module several months back, color (regretfully) is that
funky silver plum

 

I find that my '01 lw300 seems to like some gas better than others. I
usually average about 300 miles per tank (15 gallons capacity) on getty
regular grade. I got some Amoco the other day and got almost 400 miles on
the tank.
Same driving patterns so I can only assume that the engine likes the Amoco
additives better. Admittedly, this is not a scientific test. I don't keep
records of how many gallons go into the tank so MPG is vague at best.

Bad O2 sensors will usually drag down your mileage. It's also possible that
the different gas you used cleaned off a marginal sensor and improved the
mileage.
Oppie

 

Maybe Amoco pumps put more gas in a tank for a fill up.

 

Entirely possible...
Also the flow rate from the pump. On the L series, there is a variable
orifice on a float to the tank vent. It's supposed to cause the filling pump
to shut off when the tank approaches full. You can get more fuel in the tank
by filling slowly.
I'm an engineer but not anal-retentive about keeping records on mpg
<grin>. Being a bit mentally overloaded (overwhelmed) at work, I reserve all
experimental protocols for the paying job.

 

Well hopefully you arent trying to estimate your fuel consumption via
the fuel gage.