The hill from HELL!!!

Did you try the obvious - Google Maps? There is a terrain mode.

 

Move to Texas. It's so flat, you can see China on the horizon.

 

Drive up the hill and be happy you're still getting over 50mpg.

 

Don't give up! I think you will find that there are ways to deal with the situation, but it will take some research and trial and error. A lot of it comes down to management of kinetic energy, and understanding how the car works. First thing, if you can approach the bottom of the hill at a good clip, then slowly bleed off speed as you climb that will help. That may let you keep the ICE from revving into a less efficient range by reducing the power required. Try to make sure you are out of your warm up cycle before you climb the hill. In general people try to avoid using battery energy, but if you can hit the bottom with a near full battery and then use electric boost to help you up the hill (as long as you don't completely deplete it before the top) you may end up better off. The idea there is the inefficiency of charging and discharging the battery may be less than the inefficiency of having the ICE shift up into a high RPM range to get you up the hill. You may also find it pays to take different routes going up the hill and coming back down.

I am far from an expert on the subject, but here is one of my personal examples/observations. I have a friend who lives about 10 miles away, at about 500' higher altitude from my house. The main climb is right in the middle of the trip. There are two routes I can use, one freeway, one on surface streets. After trying a number of different things, I have found that I can often get better round trip mileage going to his house than I do just driving around town! I take the steeper freeway route on the way up, as it seems like just getting up over the hill fairly quickly is the best thing. I pick up speed to about 70mph coming into the foothills, and then slowly bleed off speed back to 55-60mph over the course of the climb. there are some flatter spots in which I try to pick speed back up rather than easing off the accelerator. I try to keep the ICE from revving up too much, and try to keep the instantaneous MPGs >30mpg at all times. Hobbit has shown this to keep the ICE in its more efficient RPM band at highway speeds, below this the ICE revs high and efficiency drops off quickly. I usually arrive at my friends house with about 45mpg for the one way trip, with the flats at the top and bottom helping reduce the damage done on the climb. Coming back down I take the more gradual surface street route. This is ~40 mph the whole way, and spreads the down slope over a much larger portion of the trip. I glide as much as possible, cruise in Hobbit's recommended 75mpg and less range when the ICE is needed to keep it in an efficient operating range, and usually make it home with over 70mpg for that one way. In contrast coming down the freeway route I usually only get about 55mpg one way. So overall for the roundtrip I average about 60mpg by my preffered route, vs. about 50mpg for the straight highway route.

I'm not exactly sure what that happens, but it says to me the hills don't have to be a bad thing. The ICE is at its most efficient under load, so if done correctly going up hill can actually help improve ICE efficiency. You will burn more energy overall going up, but you have to treat that hill as an energy storage device. If you then make the best possible use of that stored energy coming down it seems to me that you can end up better off from an overall efficiency standpoint compared to a flat trip.

Good luck, and keep us posted on your findings!

Rob

 

If you keep the RPM in check on the way up, and baby your regen
on the way down, you should do fine. My roadtrip last month
included going over the Rockies and random sidetrips up gravel
country roads and I still turned a real-life 57.something average
for the whole deal.
.
_H*

 

To compare apples to apples, you must compare your mileage to what you were driving before. In my case it was a Subaru Outback, which averaged 21 mpg. On your hill it would have probably gotten 16 mpg!

 

We too have an unavoidable hill just two miles from our house and it's 2 miles long with an 800 foot elevation. The good news is we have to go down the hill to get home. There's no way we make up 100% on the way down for what we lost on the way up - but it comes close. Our hill climb is on a freeway without any stop signs; I think the stop signs are your biggest problem.

Glad to hear you found an alternate route.

I also drive a 37 mile route every couple of weeks (bypassing the big hill) and that route is a slight climb most of the way from sea level to about 1,200 foot. With careful driving I can actually arrive at my destination with an increase in fuel consumption average. The way back is another story; The Prius is averaging over 75mpg on the return trip. Quite a car!

 

Assuming that you are coming back down the evil hill, you should be recovering some of that energy. You claim that going up the hill is costing you 16 mpg per tank. What is coming back down the hill saving you per tank? The difference is what the evil hill is actually costing you and is probably less than 16 mpg per tank.

 

In that case, the regenerative charging, of the drive battery, through the braking, should be recapturing alot the the energy used to go up the hill, thus making up for the lower mpg to go up the hill. It will never be 100%, but it can be significant and is how the Prius increases it's miles per gallon.

 

I call BULL! I've lived in West Texas, and it ain't flat! Not especially hilly, but definitely not flat.

Western KS - now THAT'S FLAT!

And, just to prove it - scientific research:

Kansas Is Flatter Than a Pancake

http://improbable.com/airchives/paperair/volume9/v9i3/kansas.html

 

Point to remember. As long as your trip or trips end up where you started, round trip, your uphills will aways equal your downhills, since you will always end up at the same altitude. Your grades may be different, but total enegry expended to get you up any hills will also be generated coming back down any hills regardless of grade. The regenerative braking will capture some of that downhill energy in your battery for later use. The rest will be lost in heat, brakes, spinning the ICE, etc. The grade and length of the downhills will have an effect on how much of the energy you can capture as well as the uphills will determine the energy requirements for the climb. If you are trying to determine the most efficient routes, check your mpg up the various routes and, seperately, down the various routes. You can then determine if there is significant difference worth making a choice in routes. Good luck. Let us know if check it out.