Yesterday I went from Las Vegas (2500ft) to Mt. Charleston (8000ft) My MPG started at 59MPG and by the time I got to the top had dropped to about 43.5 I said to myself no worried I will make it up and some more on the way down. And I was dead wrong...

I descended mostly in "D" then some downgrades I had to put it in "S" and the briefly in "L". I noticed that as the car was coasting downhill my MPG numbers never recovered. At times my RPM's in "D" were at 2500 and when I would depress the gas pedel it would actually drop to 2000.

In the end My MPG was 48. What was I doing wrong. The scanguage showed 0 ign and MPG at 9999 for over 10 miles.

Any ideas???

-AJ

Some thoughts that may help:

How many miles had you logged to reach 59 mpg? Remember that the mileage at the end is a running average since you last reset the odometer.

I find that if you do a lot of down hill driving the battery maxs out and you lose regen braking. I try to avoid unneeded regen by applying enough pressure to eliminate the green bars. This way the car keeps its momentum better and extends the fuel-off mode. I use the metric display which makes the fuel cut more apparent because the bars drop to one until the engine restarts. This also makes the EV assist mode more obvious too.

Unfortunately no matter how efficient the hybrid may be, you only make up part of the energy needed to climb long hills.

(I can't comment on the ScanGuage readings you gave).

Cheers,

Roger

'How many miles had you logged to reach 59 mpg? Remember that the mileage at the end is a running average since you last reset the odometer."

I had about 200 miles to average the 59MPG. My point is that ifd I climb a hill (approx 20miles) and loose 15MPG then when I go down the same hill with the engine practically off, I should recover almost all of it, right?

That's quite a drop off! Let me make sure I understand this correctly--you had 200 miles of 59mpg, you drove 20 more miles up hill and ended up at 43.5mpg? If that's the case, you averged 11.99mpg on that hill...I must have not understood correctly.

My hill climb strategy is to go between 50 and 60mph with a light throttle. I can usually keep my iFCD about 30mpg on the way up. On the way down, I try to spend as much time as possible in glide. If I notice my SoC getting too high, I will use EV-assist whenever the grade decreases to keep my momentum up and burn some volts.

Unless the hill going up is killer steep (way steeper than they build highways), I get better mileage in the mountains and hills than on flat highways in the midwest....

Like I stated in my post I went from 2500foot altitude to over 8000. These are pretty agressive hills.

I've never seen my iFCD in the 12mpg range, and I've driven quite a bit of mountain driving in the HCH--I think something is weird with your numbers.

_____________ Start __________Top __________ Subtotal ________ Down ________ Total
Miles driven: _____ 200 _________ 20 __________ 220 _____________ 20 __________ 240
MPG: ____________ 59.0 __________ X __________ 43.5 ___________ Y __________ 48.0
Gallons burned:____ 3.39_________ 1.67 _______ 5.06 __________ -.06 _____________ 5.0

In this case, X would equal 11.99mpg, and Y would equal -348mpg. I know your miles are approximations, so let's ignore the negative mpg. This baseically says that you didn't burn anything going down, but the 12mpg hit you took on the way up was way too big to overcome.

What was your strategy for the uphill portion? Do you remember what your iFCD was showing on average?

The Mt. Charleston road is one heck of a straight "up" road that goes from the desert floor to the top of an 8000 ft Mountain. How many miles is it to the top? 10?

You can get going pretty fast on the down portion. I would think that if you were braking for a good part of the time, then you were in regenerative mode and the engine was on, and that could explain the variance. I personally have never been able to recover the loss I get on a short steep climb, unless I go several times the distance of the climb in hypermile mode.