How do I achieve the best MPG when driving on hills?

This is what I measured on an 8% grade hill:

Lessons learned:

• Up the hill as slowly as safe - I like to follow semi-trailer trucks in the climb lane.
• 89 octane makes more ICE power available - the engine will tune to use higher octane fuel but other mileage may suffer. No data on 93 octane. Pure gas is almost always better.
• Descend using "B" - more for traction battery management, it also makes moderating the speed much easier. By hills, I mean 500 foot or better.
• Experiment - try different approaches and report your results. I have to drive out of town to find hills so you're in an area where you can contribute to our knowledge.
• Instrumentation - consider a DashDAQ or Scanguage or other instrumentation to gain insights. For example, peak cooled exhaust gas recirculation happens about 4,200 rpm. So this may be just over an optimum climb, rpm goal.

GOOD LUCK!

Bob Wilson

 

Near as I can tell, yes. When we next head to West Virgina, we'll use 89 to punch up the hills.

Bob Wilson

 

So for those that live on mountains, 89 may be the way to go?

 

You think you could make a graph like that for lower speeds? It seems like at speeds in residential areas with the same or greater % climbs, going slower eats your mileage average compared to gunning it and finishing the accent as fast as possible.

poor for a long time vs. really crappy for a short time factoring into an otherwise good average.

 

On a long hill with a posted 45 mph limit, I find I get far better mileage (20%) if I'm slowed down by a truck in front to say around 30 mph, as opposed to keeping up with traffic at 50+ mph!

 

Overall mileage or instantaneous mileage?

Because of course instantaneous will be better at slower speeds. But the same logic that allows pulse and glide to be efficient, it would seem that if you got it all "out of the way" as fast as possible, you are spending less time in the power burn zone.

Like if you had a glass of water, and you poured it out at a constant speed X and it took you a time T, at the end you had V units of water left in it. Then next time you have V2 units left, where V2 > V, if you instead poured out at speed X*E, where E > 1.0, however it only took you T2 time, where T2 << T.

What would the difference in V vs. V2 be?

 

Based on a the same route I drive every day, about 8 miles. When the only difference is being slowed down on that hill, I get about 70 to 75 mpg. Otherwise I get around 55!

 

Well, just the other day I decided to try not monitoring the eco graph
Instead,just driving without any big regard to mpg I achieved about -2/10 of a gal difference that 1st day,and now mostly it is higher
I am not using ECO mode button yet but will start this coming week
just to see the difference if any. Mileage is now at about 1400 and have noticed a mpg jump overall from 1st tankful(10mpg)
Tires are at 40 & 38psi.
This is my second Prius,the 1st was just as easy to achieve excellent mpg after breakin.
I fill up at the same pump when can,at the same time also
FYI the best time in the hotter months is around 6-9am
its estimated you can get 2-3% more per gal bought at these times
because of contraction in the fuel itself
There is realistically no gas available where I live that is not ethanolized.Pure gas is 100% from the oil barrel,no corn additives
It is a bit of work to get much more than 50mpg,especially like where I am in the Seattle region. Super mega hills,most everywhere so if you get over 45mpg which I do everyday,that's way more than what I'd have expected here
I have driven high mile per gallon cars for 28yrs or so
These cars are great but I do long for the day of being happy with 28mpg Honda Civics,that being said,the 2010 Prius is a charmer