The reason for this question is to decide if I can make it 165 miles after work today from Las Vegas to Barstow to fill-up. I think MTE is calculated off of a 13.3 gallon threshold (thus allowing most drivers to drive 40-60 miles after MTE is zero - though I never do more than 5 or 10 becuase I am scared )...

That said, here are some stats on my current tank. My NAV MPG has been between 44.3 MPG and 40 MPG with it currently at 42.2 MPG (where it is most of the time between 41.5 and 43.5)...

At fillup: 0 Miles Driven, MTE 616.
At 200 miles driven, MTE 430. (630 total)
At 300 miles driven, MTE 300 (600 total)
At (current) 390 miles driven, MTE 195 (595 total).

I know why the first 200 miles driven is so high, all I was doing was running to and from work with few errands, etc. My work drive probably nets somewhere in the neighborhood of 47 MPG (both ways)... Between 200 and 300 there was a few errands that might have the car in the neighborhood of mid 30s MPG and the last part of the drive was an out and back up a big "hill" (for 10 miles)... MPG there is probably 20s and back 50s, but becuase of the inital fall I think that it takes a bigger overall hit. When I returned home (from the round trip) my MPG was exactly the same as when I pulled out 42.0 MPG...

That said. How much fuel does everyone think I have used? I presume a subtraction from 15 gallons should garner the (aproximate) gas left.

FYI my last tank was about 41.3 MPG so I use this in some assumptions.

Here are my guesses. I feel pretty confident that I am 41 MPG+ for this tank, so I presume I can take total MTE (miles driven + MTE) and divide by 13.3 to get an aprox current tank MPG. In this case 595/13.3= 44.7 (seems high, but I think I might have overfilled a half gallon last tank)...

If the above number is true then I should be able to drive 595 + 1.7*44.7 or 671 miles on my tank. Not sure I would want to risk that but I'm curious if I am in the ballpark. If I presume my tank is what is says on the NAV it would only provide a 42.2*15 or 633 mile tank...

Now I know everyone says the NAV MPG is off by 1-2 MPG becuase it weights the more current results too heavly, however, if my driving is pretty consistant then I think that it should be more accurate (same routes, same errands, etc).

That said, here is my ultimate question. I'll run home 15 miles from work, giving my tank ODO 410 miles. MTE should be about 180. Presuming I drive at 30 MPG for the next 165 miles would I be able to make it? Can I make 95 miles? What about if my MPG for that part of the drive is 25...

Please feel free to chime in. The wife wants me to fill up here, which I will of course do anyway (why risk running out of gas in the Southern Ca desert), but I'm just curious if I could make it.

Thanks in advance.

 

On my 05, the MTE seems to be based on 13.7 gallons used, not 13.3. From your current MTE + trip, your MPG is 595/13.7=43.4MPG. @40 MPG, you would run out of gas at about 52 miles beyond when MTE went to zero. There is a chance that the 08 is different, but the MTE calculation in my 05 is very accurate, more so than the nav or instrument cluster average economy. That is, once you are into the tank a hundred miles or so.

 

Thanks carl... Yeah I actually ment 13.7 (with 1.3 reserve)... I don't know why I typed 13.3 and did my calcs from that... Too early in the morning perhaps...

So would you say it is pretty accurate to assume that at this point in the tank I am 395/43.4 or 9.1 gallons used with 5.9 gallons left?

 

That's probably a pretty good guess. As an example, right now in my 05 I have the following:
Instrument Cluster=40.4MPG, NAV average=41.0, MTE=387, trip=138.5,
and Scangauge tank=38.7MPG (with 3.3% fuel calibration.) The MTE+trip/13.7=38.4MPG, which is very close to the Scangauge tank MPG. Once you are into a tank a bit, any over/under fill is out of the picture for the MTE calculation. Overfilling can give a temporarily high MTE, but eventually it comes back to earth as you go through the tank.

 

That's good mileage for an '08 and it's nice to see others getting over 40mpg tanks. No one with a '08 or '09 FEH/MMH that I've seen post has verified the 0 MTE and the 1.3 gallons remaining. I ran out of gas I think on my third tank in my '09 FEHL with only 37 miles past 0 MTE. The reason I'm not sure is I got the "Stop Safely Now" warning and could only reach a max 20mph speed in EV. In my '05 FEH, I got no warning and I was able to go 40mph in EV on I-95. Both vehicles had a low SoC also when I ran out of gas. My '05 had 56 miles past 0 MTE, but I had a spare gallon of gas with me just in case.

I know for sure I was out of gas in my '05 because it would restart for a second but die right away. After I added the gallon of gas, it started and ran fine. I was lucky that I made it to a gas station in my '09 and didn't think to make sure it was out of gas by trying to restart it. For this reason I can't verify I was totally out of gas when it went to "Limp Home Mode" only at 37 miles past 0 MTE. I was averaging 46.4mpg on my Nav Sys and 49.0 on my SG with that tank, so if I had 1.3 gallons left I should have gone much further than 37 miles. One other thing, I was stopping fast for a stoplight when this happen and the gas could have sloshed causing the fuel pump or injectors to lose pressure causing the warning and LOS (limited operating strategy).

Why don't you carry spare gas and verify for us all the quantity of gas in the '08 past 0 MTE? I may try this in my '09 on my present 4th tank.

Here is what I'm seeing on my gauges right now on my '09:

Dash - 2466.5 OD and 503 trip OD, 153 MTE, and Nav MPG average 47.2

SG - tank average 50.4mpg, tank miles 502, 252 miles TTE, 5.0 gallon TTE, 9.95 gallons used.

GaryG

 

Even with my non-hypermiling wife doing 98% of the driving (all rural, minimal hwy), this suv is really getting insane mpg in comparison to our previous FEH, especially with the cooler air coming in (Florida cooler)...

I never thought over 40mpg was possible for the "regular" driver.

 

It's still pretty hot down here in the Palm Beach area, but I can't wait till it cools off to see some really high MPG. Not sure where you travel if there are any rolling hills, but these flat roads here are MPG killers. I use to think I had an advantage here, but not true after driving the MPG Challenge with E-10. My '05 FEH MPG was murdered here with E-10, and the heat just buried it. The '09 handles the E-10 and the heat much better, but I'd love to see what regular gas and cool weather would do together. My last fill-up put my MTE at 648, and it was right on or just a little low for this 4th tank.

Complete fuel cut in "D" is starting at much lower speeds now at a little over 40mph and I can feel a jerk at about 25mph when fuel starts flowing again. It's feels like a restart from EV in my '05 FEH. It does the same thing when going from fuel-cut to EV when there is enough SoC to go EV. What's crazy is you can be getting regen while in fuel-cut decelerating. This is great when there is not enough SoC for EV, but your not burning any gas while charging the battery.

I love the moon roof for venting a hot interior and getting air circulating with less drag with the windows all the way down.

GaryG

 

Gary,

We have been high 70's to mid 80's on the West coast (of FL) and the truck loves it.
In your post you said that the flat hurts you and the hills help, but I think that is only because of your knowledge on driving a hybrid.

In the case of my wife driving, I am certain that the flat roads are helping her achieve such great numbers. She uses the cruise at any speed above 30 and her mileage in this one (2009)over the last one (2008)is much better. (3-5mpg better).

I would add that we are only just under 2500 miles and the mileage is already increasing from new. These were numbers that we saw in the 08 with over 10k miles, not so early in the game.

One of the things I noticed is there is much more electric assist in this one YET it's not electric assist from the BATTERY. The last truck, under load used much more electric assist directly from the battery. On this one, there seems to be more power available to the electric motor from the ICE. In fact, sometimes when the assist line is "thick" from the electric motor to the wheels, the battery isn't even "lit up" or providing that assist.
Having just come out of the 08, it's pretty interesting to see the different characteristics of each one. I would like to see a "technical" write up on the changes in the programming.

I would also add that when driving along, with the ice running, the inst cons is usually in the 40+ range (remember the roads here are VERY flat) which means once you get going, there is very little load to keep moving.

I really think that when driving here on the west coast that the wind is my biggest mpg killer, much more than the roads, especially above 40mph...


Sean

 

Sorry for the late update, but I am fairly convinced after the last two fillups that the MTE does not compute off of 13.7 gallons but rather 14.15 or so...

I filled up at 410 ODO with a 175 MTE which should have garnered a 43.3 MPG... However after putting in 9.79 gallons of gas that got the same MPG as my last tank, 41.3... The last tank I had similar numbers, but filled up at about 585 miles, about 3 miles after MTE went to 0. I filled up 14.2 gallons. That said I'm really thinking it is 14.15 gallons on the MTE calculation...

Gary as you said, if you ran out of gas after 37 miles that would have been about .8 gallons for someone averaging 43 or so MPG...

That said, I might have been able to make it to Barstow after all, it would have been close... To give my wife something to do, we wrote down how many miles we drove each gallon of gas (via the NAV MPG, with a reset on it and the trip ODO when each values matched)... For reference, up the hills I held the RPMs under 2500 (mostly at 2400) and down the hills or on the straight streches I set the cruise at 62. When I could follow a truck up the hill I attempted to draft at a safe distace. Also, most of the drive was into a 20-30 mph headwind... Down the hills I would use 1600-1800 RPMs to build speed and do a P/G between 70 and 60 MPH... Here are my results for the 265 mile drive.

(This kinda shows the extreeme elevation changes)
1: 27.8 - included a bit of in town driving to the interstate
2: 27.6
3: 43.0 - down the "baker hill"
4: 30.1
5: 28.1
6: 27.9
7: 37.3 - down the "cajon pass"
8: 43.0 - from Ontario (900 feet) to the ocean...

It looks like my tank average was 33.13 or so... We will see if this is accurate as I will track each gallon of gas when we are down here until we leave sunday... I am thinking that this way to use the NAV will provide accurate results... If I can remember correctly out ODO is 269 (or so) and a MTE of 222...

Checking my 14.15 assumption... 33.13*14.15=468, which is somewhat close to 269+222, but I assume the 80 miles on the last 2 gallons really influenced that...

Maybe this helps...

 

Sean, I agree with everything you just posted. I have always used the bridges and my strategy to climb up and coast down to pump-up my mileage. I've talked to many truckers who said the same thing about driving in the hills verses driving on flat roads. These guys said they used much more fuel here in Florida than they do in the mountains. They climb using those low RPM's and diesel torque and fuel-cut on the way down.

The '09 FWD FEHL is also great (better than my '05) in cruise control. You know you can now set it as low as 25mph don't you? On flat roads, the PCM controls RPM's for better MPG now and also uses less energy in EV. No question your wife should use CC whenever possible in the '09 FEHL here in Florida. This P&G in CC improves mileage because of fuel-cut, so that's why I use it. You've got to try setting the CC at the minimum speed for traffic and then when the engine starts, slowly increase (1,400 to 1,600 RPM's) your speed ~3mph and glide down to the pre-set CC speed. If your CC is set at 40mph or below, just stop P&G when you fall into EV.

Yes wind is both a problem here as well, but much less because the '09 has more engine power and much more EV power for setting the CC at 40mph. It's only going to get better as our '09's break-in. We both have about the same miles on our OD, and I can also say there is a big improvement in mileage and stronger EV.

I'm almost sure the '09 FEH/MMH has much of the same converters and programming as the Plug-In's Ford is testing with California Edison. The small generator (MG1) now provides more assist than earlier models, thats why your seeing it on the energy screen. This is real smart of Ford because the generator can boost high voltage AC to the traction motor without draining the HV battery as much. This also reduces battery heat.

GaryG