Billyk24, Gotcha. I only do that slow accel and driving the speed limit thing in the right lane of multi-lane city thoroughfares (so the impatient guys behind me can easily go around -- and they do!). If I'm on a two-lane, I'm more considerate. This time of year in South Texas I'm so spoiled I HAVE to have the A/C on at least in the "Econ" mode, and that causes the engine to come on fairly frequently to keep the cool air coming. I figure any time the engine is running it's providing some charge to the battery.
Your point is well-taken.

 

Gary and others -- another quick update. I worked my way through the rest of the tank of gas I was using when I first joined this thread a few weeks ago. I've kept the A/C on Econ and driven as conservatively as I could but not hypermiling. After resetting my Average MPG reading to zero I was able to get the reading up to just over 24 (all of this is in-town driving). When I filled the tank I calculated the actual mileage for the entire tank to be 23.9. Not good, but a whole lot better than the previous 19.1. That tells me (I think) that my driving habits had deteriorated, plus I had NOT been running the A/C on Econ so the ICE never stopped.
I had almost forgotten the 12V battery, but remembered and put a volt-meter on it when it should have been fully charged. It only showed 11.5V! I had it tested, and sure enough it was very weak under any load at all. New 12V battery now installed (the same day I filled the tank). I re-zeroed the Average MPG reading and have now put about 35 miles on the FEH. The Average MPG reading right now is 28.5! I think my problem is solved.
Coincidentally my new ScanGauge arrived on Monday and I began its calibration with the fuel fill-up. Once I get comfortable with all its functions I may have some additional data to report, and almost certainly some questions.
THANK YOU for your patience and advice! It is MUCH appreciated!
John

 

Your welcome John!

One last thing, the '05 - '08 FEH engine takes a big hit on MPG running on E10 (10% Ethanol). If you can find 87 octane without ethanol, your MPG will improve. The '09 and newer FEH runs just fine on E10 because of a newer broadband 02 sensors.

Gary

 

Gary, Mine's an 09, so the E10 ought to be OK. Just about all the pumps I've seen now state "Contains up to 10% ethanol."

John

 

I forgot that when I pulled your window sticker you had an '09.

I sold my '09 FEH Limited and got the '13 C-Max Energi. In my opinion, the '09 FEH is the best FEH ever made. My best tank was 65mpg, going 884 miles on 13.6 gallons of E10. I had a lifetime 53.9mpg at 31,000 miles when I sold it. My C-Max Energi with a smaller 2.0L can't get near the MPG in hybrid mode that the '09 FEH got hypermiling.

I kept all the workshop manuals for the '05 and '09 FEH's, so I could still help with problems like you had.

The group here at GH will help you anytime, but put the year FEH you have on you sig page like I have on mine.

Gary

 

I've never had any prob with E10 on my 2008. Mileage under 28MPG would make me look for a flat tire or 2! ....but more seriously, I wonder about your tires to consistantly get such poor mileage. I've never gotten less than my present 28MPG on my 188,000 mile '08. Nothing affects mileage like tires, dragging brakes, or bearings. Seriously. I drive 70+ mph probably more than 50% of the time, and that's sure not the ideal way to drive an FEH. I realize that my driving conditions for the last 2 yrs are a poor match for my FEH (75%+ highway).

Keep working on it. Your description of your "test mode" mild driving with little/no A/C and still mid-20s mpg tells me that you've got something wrong with the vehicle itself.

 

[QUOTE=hcbflash;251190]Nothing affects mileage like tires, dragging brakes, or bearings.


Nothing effects mileage (mpg) like real cold winter weather. Single digit (F) and below can be a real eye-opener and a huge difference between temperatures in the mid 30's.

 

[quote=Billyk24;251193]Oh Yeah. With 40+ days so far this winter where temps have hit below zero and around 20 consecutive days with below zero temps at night, I'm seeing tank averages of 20-23 MPG. But hey, thats still way better than I would be doing with our other vehicle (an '05 Town & Country minivan), so I'm not complaining.