MPG Freeway Incline Help

I've been hypermiling for a couple years. All I can say is ... driving up long, steady inclines is always going to hurt your fuel economy. There's no way around it. The best thing to do I would say is to hold your foot steady and watch your instantaneous milage. Adjust to get the best mileage (without going to slow.) I just got my Prius but I don't think there's any special tricks when navigating long grades uphill.

 

Maybe it's as simple as having too low tire pressure? That has a huge effect..

If not, once your tires wear in a bit more and you refine high MPG hill climbing skills you'll for sure get better gas mileage. (Hint: it's safe to overinflate tires a little more than recommended, will give better MPG). Also consider trading in your stock tires for higher quality low rolling resistance tires.


And if you install a scan gauge or get a Torque app setup in your car you'll have more info with which to fine tune your hill climbing technique. For example there's an ideal range for engine RPM for hill climbing, sometimes it means going up a hill faster than an MPG conscious driver would think is efficient but you'll need a scan gauge or the Torque app to see your car's RPM.

In time you'll also learn how to maximize MPG on your downhill drive too. The cruise control can teach you a few things if you watch how it effects use of battery and engine while keeping a steady speed...

Lastly, you may have perfect weather for MPG in Los Angeles proper year round, but once you head up into those mountains it's more likely you'll hit more winter-like temperatures, which I've found tends to take a nice big bite out of my MPG efforts. The mountains of Northern California kill my MPG this time of year, but once I'm in the Sacramento Valley MPG goes thru the roof!

I'm sure once Spring and summer heat up you'll see MPG improve, unless of course you start to use your air conditioner too much.

Most of all enjoy your new car! And remember most every one of us got sub-par MPG when we first started driving our Prius. It took a while...

PS: I've not heard of the egg related MPG improvement technique? where can I learn more? Hopefully it's the same as pulse and glide? Or using stealth mode at freeway speeds?

 

Drive as if an egg between your foot and the gas pedal, and do not break the egg.

 

The only two things I can really think of are Tires, inflate to front 40psi rear 38psi and just remember speed kills gas mileage!

 

I suggest you read the information on MPG in this forum. If you warm-up the car and accelerate too slowly you can negatively affect your MPG.

 

It sounds like a long, steady slope. In that case, the best you can do is pick a speed you can live with and keep steady at that speed. Your mileage will be low because you're climbing. The same thing happens to all of the other cars on the road.
On the other hand you have the opportunity to get more of the energy back than the other cars in your morning trip though.

 

40 is nothing to write home about. is all your driving on the freeway? if you're getting 80-90 going the other way, shouldn't your average be higher? try resetting a trip meter and doing some off freeway driving just to make sure your car is okay.

 

oh, well that won't get good gas mileage at all... The duration of your accelerating will go on for too long and you'll waste gas. It's best to use acceleration for as brief a period of time as possible. That little Prius engine is most efficient at 2/3 rds of full power. So you'll get better gas mileage with heavier acceleration (pulse) at first and then gliding (lightly touching the gas peddle). Here's some links that explain the details of high MPG....

2010 Prius Pulse and Glide warp stealth help | PriusChat
glide question | PriusChat

 

I understand I was just answering your question about the egg theory.

 

What are the "high MPG hill climbing skills," though? I think that's the question (and one I have had myself). P&G doesn't seem to work well because you lose speed too quickly. Is it better to do a modified P&G alternating between pulses of more throttle and glides with the HSI at around 1/2? Steady throttle just enough to maintain speed?

Obviously hill climbing is always going to hurt economy - what's the best way to minimize the loss?

 

Near as I can tell it has to do with studying the CAN data, or Scan Gauge data, or Torque app data... There's some sweet spots for better MPG at certain RPM as relates to certain throttle positions... I read what the most efficient RPM was for hill climbing on a thread on here once but can't remember what it was, though it's much higher RPM than you might think and climbing a hill faster can sometimes be more efficient than slower. Soon as I can watch my RPM's with an extra device I'll start experimenting...

 

I suggest a higher speed (more power) to get off the incline asap but stay out of the red zone if you can. Wherever you set the throttle you are going to lose speed. You'll want to time it, if you can, to have the battery down to two or three bars when you stop so you can use the downhill grade to charge the battery.

 

Why are you worried about one-half of your trip? You can get very high mpg on much of the downhill leg, mpg could be 70 or even 80. I live near Sacramento and make 200 mile round trips to Lake Tahoe (7400 ft elevation max, lake at 62oo ft. At the top of the pass mileage is down to 33 mpg). Going up on a good day I get about 38 mpg, returning on a good day (last week) 80.5 mpg. The round trip was 54.5 mpg. (Okay, subtract 3.7 mph average display error.)

 

i think your round trip still averages a good mpg number (50 at the very least). The best technique which others have already pointed out is to:

1. get as much momentum as possible approaching the climb and reach your target speed. A bit of power zone is ok for a short while to make sure you don't use it for long periods accelerating uphill.


2. since it's a long, long climb, try and hold that speed, keeping one eye on the HSI level to the very minimum that your speed doesn't drop until you're about to reach the summit. Before you reach the summit (a mile or two. it depends on your judgement), gradually release the accelerator in minute increments so that you slowly bleed off speed.

3. If it's traffic, look far, far ahead and "drive with buffer". That means a fair bit of space between you and the car in front. Pulse and glide just enough that once you catch up to the tail of the car ahead, he's already accelerating again and you're glide won't be hampered as you start to pulse again yourself. Just make sure that you buffer in such a way that you keep a net moving speed. Once you stop, you will have lost all that momentum and it will take lots of energy to go get back up to speed again. This is what kills mpg.

It's trial and error, but once you get the rhythm and timing right, you'll see your mpg improve on that stretch (high speed or low speed situations)

 

Yup, I hate that drive from Alvarado Street to Glendale. Luckily, I don't make that drive very often. I do one of 2 things: (1) Don't pay any attention to my MPG and just drive. (2) Though many recommend the pulse and glide technique, I like just following traffic in the far right lane (whatever speed that happens to be). I think your (our?) problem is that the road really isn't that "steady" of an incline. So traffic, even in the right lane, will go slow, fast, slow, repeat. Almost a built in pulse and glide.

I've tried to watch my instantaneous MPG and "try" to keep it as high as I can, which usually isn't very high. The problem with that is that I'm not watching the road all of the time. That's not good.

Mike

 

For traffic jams and super highway speeds, you need a very sensitive throttle response time so set your Prius to PWR mode.

For a long uphill climb (straight incline up with no downhill segments with no stop and go traffic) P&G wont work
[ the most important thing you can do to help your FE is not to accelerate uphill]
1) before starting the long uphill climb, give the Prius a running start - pushing it to your target speed before the Prius starts the uphill climb (or accelerate as quickly as you can without going into the red zone at the bottom/foot of the hill if this is not possible )
2) set your cruise control on.
3) set your target speed at the posted speed limit or slightly less and drive in the slow lane (You'll get better fuel efficiency driving at a lower speed like 65 mph than at a higher speed like 75 mph)
4) When the Prius gets to the end of the uphill climb, turn off cruise control and coast.


If your commute has stop-n-go traffic under 25 mph - you need to study how to do mini-P&G cycles.


In theory, the MPGs going downhill (to work) should compensate/lift up the MPGs going uphill (from work) so your Prius should be getting about 48-55 mpg per tank. However, if you are driving over 70 mph on the downhill to work then aerodynamic drag is likely eating away at your downhill gravitational advantage going to work and making your overall AVG MPG suffer. To get better OVERALL fuel efficiency for each tank of gas you need to accelerate more slowly going to work since you will naturally accelerate a bit faster while going downhill - synch your accelerations while going down hill but see if you can stay at the posted speed limit without getting into trouble. While trying to stay within the posted speed limit, avoid braking regeneration while going downhill but - instead allow aerodynamic drag to slow down the vehicle. The energy loss from regenerative braking is higher than the energy loss from aerodynamic drag at speeds under 75 mph.

hope this helps

Walter

 

I think you need to focus on the downhill maximization of mpg if you can get 99.9 for that portion it will help its an uphill battle

 

I have been driving up the SR-2 since 08! Think of the positive, you should be able to go down the SR-2 at 99.9 the entire length! I do it every morning, and my avg is 48.X in summer. In winter it drops to 42!
Unless mobius reinvents his loop, the 2 is always going to be a pain in da nice person!!!