Lifetime MPG jump. WHY?

[sheafe.ewing]

I'm the original owner of "00 #2360. For years I "complained" about my low lmpg which has stayed at around 51.9.

I went to this group, then to the "other one," for assistance; followed all suggestions to modify driving habits, increase
tire inflation, etc., etc. Eventually, after warning light stayed lit, had the battery, BCM, ECM replaced Dec. '07 (warranty)
at 37 K (yes, low mileage) Soon after, I began to have surges at about 30 mph; becoming more frequent.

I read that EGR can require cleaning/replacement to eliminate this problem.

I reasoned I should bypass the cleaning maneuver, go directly to replacement, and did so (with photo-instructions
by David Judd.com)

Mirabile. Surging has stopped.

Even better ! ! !. After resetting a trip meter, I began noticing a big increase in mpg. Now, as of putting > 250 mi on
the Insight since EGR replacement, my mpg has improved to 57.8. This has happened while driving over the same-old routes,
without changing driver or driver-habits. (Mixed city/freeway/ 800 ft altitude climbs, descents on return route)

If this is, as I think it must be, because of something inherent in the function of the EGR, I wonder why it hasn't been
reported before. Quite the opposite. Others have remarked that, although surging has been successfully eliminated, there
hasn't been a change in mpg. Well, it doesn't seem so for me, and my Insight.

While 250 mi may not be a real "test" of lasting improvement, I give this "preliminary" happy report of a positive upswing in lmpg
after a "lifetime" of low-end mpg.

[IamIan]

remember the life time MPG will include all those cold winter days when you get very very bad MPG... resetting the trip meter as you said you did , starts you at that point... and thus it no longer being hard core winter... I would expect and have seen in my own commute an increase in MPG... You will always get much better MPG under the same conditions in warmer weather.

[sheafe.ewing]

remember the life time MPG will include all those cold winter days when you get very very bad MPG... resetting the trip meter as you said you did , starts you at that point... and thus it no longer being hard core winter... I would expect and have seen in my own commute an increase in MPG... You will always get much better MPG under the same conditions in warmer weather.

Where *I* live, we don't have "hard-core" winter.... occasional freeze... never long periods below 45 degrees F, rarely highs of >105.
I have long since removed temp-swings from the cause-list for jumps in mpg, since even before the EGR valve replacement, I had never seen
temp-swings during seasonal temp changes.

Appreciate the thought, however.