For what it's worth (for the record and to give the 10dah a little comfort factor next time even without the gallon in the trunk), I headed out in our HAH after my wife had forgotten to gas up (even though the low fuel idiot light was glowing for quite some time)...luckily made it to the closest gas station with the "range" indicator on the trip computer showing 4 miles. Has anyone here seen the range indicator any closer to zero? Do you suppose it would run out of fuel at exactly 0 miles? I wished that I had the gallon in the trunk just so I could test the accuracy to to see how low it would go...

 

ref post # 8...

brick: I agree that DWL is a very good technique generally. My thought is that with CC on with a reasonable downhill, the engine is **** near zero fuel flow- like foot off gas for in gear coasting (a la DWB). In opposition to holding the same fuel flow in DWL to pick up extra speed on the downhill, so as to carry that energy into the next uphill. For many terrains, the benefit of each is about the same- you either use less fuel on the downhill (CC) or use less on the uphill (DWL). I say ABOUT the same.

One of the most interesting, and in the end, highly accepted, statements to come out of the Ford Hybrid day back in the fall was that they STRONGLY recommend using CC for almost all situations. None of their test drivers have ever been able to beat CC's fuel efficiency on any terrain in any of their vehicles, excepting one very hilly course that yielded something like a 0.2mpg improvement over the CC. Yes, a human can anticipate cresting, etc that a machine cannot, but the machine has far more precise control over exactly how much fuel to meter in at all times, as opposed to a foot that gets tired.

Given that, and my own empirical experience, I let the computer do the work. If I suffer 0.1 or 0.2, I'll live. Or just slow down another 1 or 2mph to compensate. (I drove for 6 months DWL and never using CC. You can see the lack of difference in my fuel logs.)

But like I said, DWL does work. I've just found that CC works about as well, for less effort. Preference.

 

Thanks Navy, somehow missed that post #8. "Dashes" for no more than about 20 miles and then you're walking. Good to know.

 

In support of using CC, it must be said that there is another advantage: your speed is pretty much constant (+/- 1 or 2mph) which irritates other drivers far less than the wider swings that come with DWL. I'll have to give CC @60mph a shot and see how it works in my car.

When my dad picked up his XC70 the sales guy was quite clear that cruise control should be used. He said that it could make a 3mpg difference vs. using your own foot.

 

yeah, but in general I'll accept a salesperson's word about anything more technical than how to turn on the wipers about as far as I can throw him (and I'm a pretty puny guy). In this very rare instance he happened to be correct

Brick, the way your technique is changing and mileage is improving, I would suggest that you keep refining things, and once you've reached a semblance of steady-state FE, then try CC and do a comparison.

Oh- and 60 is far from optimal for the HAH, at least. Ideal would be right after lockup, about 49mph on the 5AT. But I can't bring myself to go that slow most days- even I get frustrated sometimes. Those few times I am at 50mph for a decently long segment, my FE is far better- >50mpg becomes easy when flowing at 50mph, especially if following a truck.

 

I just did another 500+ mile tank today. 505 miles. 13.424 gallons. 37.6 mpg. I forgot my camera at work, so I don't have a pic to post. Perhaps, I'll take a pic with my camcorder, but the resolution will not be that great. I've found the pics it takes come out pretty grainy.

Something I noticed, but I don't know if it's correlated, is that I get better FE at night. The traffic flow is about the same. I set cruise at 70 mph most of the way. But I seem to get 35 mpg during the day and 38 mpg at night. The temp difference is usually around 10 degrees day/night.

I also noticed my Trip B (never reset it) has finally reached 30.0 mpg!

 

way to go.

In your case out in hotville, rolling resistance may decrease at night as the asphalt cools? In general it makes sense that FE peaks somewhere around 'normal' temps and drops off on either side of, say, 75deg or so.

Also...is theis a reverse of the daytime trip? elevation/wind...?

 

Just did ANOTHER 500+ mile tank.

553 to be exact. I think I could have pushed fourth and exceeded 600, but I was in the desert and fuel stops are pretty far spaced apart.

The asphalt cooling makes sense, but 3 mpg worth? I notice the increase no matter which direction I travel, and always at night. Perhaps, the variables have always just been right for me while traveling at night?

Something else I noticed. Sometimes on extremely flat roads, my FE stays the same around 37-38 mpg. But then suddenly, it starts dropping 0.1 mpg at a time during every refresh. It does this until around 34-35 mpg. Then slowly builds back up. Looking at the FCD, I don't see any activity. The meter stays around the 40 mpg range the whole time. Tonight is the second time I've noticed it and watched it. But I think it's happened in the past, as I've only caught the tail end of it before. Anyone else ever noticed this?

 

the display on the dash starts to drop, or the navi?

the dash might be reacting to localized rounding errors in calculating how much fuel is consumed? Or...the eternal 'looks flat but ain't' problem?

3mpg would be a lot for RR changes, I think your guess about the planets aligned properly is more like it...

 

The display on the dash. The FCD stays the same throughout all this.