Max MPG techniques?

The following is an excellent post efusco made last year. It's running around somewhere in a thread on this board and may have been included in a FAQ that has since been lost.


1)Be patient. There is a signficant break in period for the car (engine, bearings, perhaps even some computer 'learning'). Also, there is a break in period for the driver. You have to get used to the feel of the engine, when it's over reving, under reving, etc. Your anticipatory driving and braking skills will improve.

2)If you are enjoying relatively moderate climates turn your AC to OFF. To keep a 'vent' on do the following. Push the Climate button on the MFD (multi-function display (the monitor)), if the AC button is lit, turn it off. Now push down on the temp setting until you hit MAX COLD. If the AC turns back on, turn it off again. Now, you can touch one of the fan speed buttons..I rarely need anything stronger than the second or third button from the left unless the car is really warm from sitting in the sun. I saw an almost 4mpg immediate improvement in gas mileage by not leaving the AC on all the time. Of course, if it's really hot or really cold and you need to use the AC, then, by all means, do so. Also, avoid the defrost buttons as much as possible, they really chew up power.

3)Consider adjusting your tire pressure to something in the range of 40F/38R (I use 42F/40R, others go as high as 44F/42R). I find that it improves handling and there is some evidence to suggest improved mileage and longer tire wear. This is a bit controversial (see the current thread), but it works for me and many others.

4)Drive casually--Look ahead, is the light likely to change to red before you get to it? If so, start coasting or breaking as soon as you see that. Your ICE will shut off sooner, you'll begin regenerative braking sooner, you'll reduce hard braking which can wear your friction brakes faster. Don't gun-it to pass people, don't drive in the fast lane. Try to avoid situations where you need to accelerate quickly for lane changes.

5)If where you live is relatively flat or you have extended areas that are pretty flat, use the Cruise Control. It helps avoid fluctuations in speed that can use more fuel. If you're in a hilly area it can be much better to AVOID CC--don't try to maintain speed over hill crests, just coast over them and let gravity assist you to regain speed on the downhill. Now, don't take this advice to any extreme, but often I find that as I'm approaching the crest of a hill, the ICE will have to really rev up to maintain 45mph, whereas if I take my foot off and 'feather' (see below) the accelerator I can hear the ICE actually shut off, and I can still maintain up to about 42-43 MPH, hardly any drop at all and I used no gas. I can then, often, pick up speed again on the downhill side while still coasting. This takes practice and a bit of a learned touch to avoid pissing off everyone behind you, but in the right situation and with practice becomes very natural.

6)Achieving Stealth is not, necessarily, a good thing. It is less efficient to use the battery, in most cases than the ICE assuming all the power from the ICE is being used for accelerating/powering the wheels. There is some loss of energy inherent in the transfer from ICE to batt. to wheels. That said, at times where the ICE would otherwise be running inefficiently (low RPM, excess energy going to the battery) then Stealth may be the best situation.

7)Another situation is coasting. If you take your foot totally off the gas while watching the energy screen you'll notice some regeneration going on and slowing of the car. That's fine if you want to coast to a stop over a distance, but one can also learn to 'feather' the pedal to coast. Let your foot totally off the pedal briefly, then very gently touch it back down until you see all arrows disappear on the Energy screen. You'll notice that you do not slow nearly as fast as with the foot totally off, you're using no energy and the only thing slowing you is internal friction in the car and the air friction acting on your 0.26Cd car. You can coast a good long way with very little loss of speed. This is another good plan when you have a long way to a light that you know you may need to stop at but don't want to start braking yet.

8)Switching to synthetic oil may gain you a tiny improvement--most likely not enough to justify the cost of the oil over mineral oil. There is a tiny added environmental benefit to synthetic. There may be some improved engine life if you plan to drive your Prius for 350k miles plus. I use it, more or less b/c of the environmental thing and b/c it seems like the most technologically advanced product for my most technologically advanced car.

 

Generally the best range of speeds to get maximum mileage is around 40 MPH... the terrain affects your mileage heavily as well.

Do a search for Pulse and Glide... basically the technique is to accelerate to 40 MPH swiftly, and then let off the throttle just enough to enter "glide" mode... where basically the motor-generators are running free, the engine is stopped, and your car is essentially in neutral... glide for as long as you can, maybe until you drop to about 30 MPH, and then "pulse" back up to 40 MPH using the ICE. rinse and repeat.

 

Just one little thing to add, as it wasn't defined in either post:

ICE stands for Internal Combustion Engine. Just saw that acronym being thrown around but it was never defined.

 

download the userguide at the bottom of this page is useful too http://john1701a.com/

 

How long is the break in period?

Also my salesman said not to use the cruise for the first few thousand miles. It is required to have variying RPMs to break in the engine..he was kinda clueless on other aspects of the car, so I'm not sure I believe him.

 

Your sales person is less than adequately informed. Unless it is dead flat even at highway speeds all you need to do is watch the energy monitor and you will see the ICE, MG1, MG2 changing all the time. The book says avoid rapid acceleration and deceleration or words to that effect. Just don’t put your foot in it unless you have to.

 

Some time ago, on one of the Yahoo lists, I was told 8,000 miles was the magic number. I did see an increase at that point, but that's also due to the weather at the time and probably other factors (like learning how to drive it to the best advantage).

 

I have not really experienced the down-side of the break in period... I've been averaging 52+ since the first tank (thanks in great part to reading this forum while I waited to take delivery). Hoping I'll see higher after the break in and once temps warm up.

 

Where are you located? If you have a lot of hills, don't expect to match the gloating owners with 50 mph+ who live in the flats. I deal with hills daily--routinely climb up and down from sea level to 500 ft; and many times up down from 1000 ft--and my overall MPG average never gets over 41 mpg. I use all the techniques found on this site whenever possible, and they have helped a lot on trips away from home. Anyway, just letting you know that hills have a BIG impact on our MPG.

 

Maybe someone can help me on this. I just got my car on Friday (Wed. now) and I'm having a hell of a time getting it to coast. I do exactly as he said. I let up on the gas then just every so slighly hit the gas till the arrows go away. Sometimes it works just fine. No problem what so ever. Other times it seems no matter how every so slightly I press it, it will go from regen to ICE or to the electrical motor. I thought maybe it was because I had the heater on and it needed the extra energy to power it. (It is cold here in Michigan.) So I turned it off and then it seemed to coast fine...then later it didn't and I was able to with it on. I can seem to get it to coast easier at slower speeds <35MPH than at highway speeds. I love the car and it is very fun to learn the ins and outs.

 

Efusco it is again I ask that you repost your levels of Prius mastery, then pin it, you have the power. I am not going to do it but I thought it was very insightful. You put your finger on every level of driving that I have gone through. It really was good, and sad that it was lost.
Getting to "Pulse and Glide" and "Dead Banding" takes a bit of time, but it can be mastered. All the tools are built into the car. Keep practicing, it can be done, it can be mastered.

 

Eninge temp seems to have an important role. I've noticed that in the early part of my short communte I can't get grey (no arrows). Typically I get pink arrows from ICE to wheels and green to the battery and the mileage sucks (~40 MPG) even though I'm not pushing the car hard at all. I also have noticed that it's hard to get just the battery to power the car early on in the drive. I think the car just wants to run the ICE as much as possible to get the engine warm and get the emissions gear heated up. Later in the commute I've got a sweet downhill run and by then I can "deadband" easily. Of course, by then I've driven up a rather large hill so the engine's been busy.

Above 42 I think that MG1 has to do something (sorry for the lame vagueness here) to protect itself from spinning at more than 6500 RPM.

 

I would like to share a little bit of insight here with the info I see on CAN-View.

During winter time and if you have the heat on (for example, set at 70 F), you can not get ICE to stop unless ICE temp is above ~145 F (~62 C). When I am driving alone, I usually set temp to max cold (or just stop a/c) when I know I am coming to a stop to help ICE stop (used so many "stop"s... well.. it's 1 in the morning!). Temperature is around 20's to 30's this week in NY, and I manage to get 48.7 MPG with couple of short trips (<1mile) between buildings at work.

ICE will spin no matter if you step on gas or not at speeds above 42mph. RPM is very close to 1k when you glide above 42mph, which is consistent to what was discussed before in other post.

When I glide (no arrow) under 41mph, I observe a current drain (current coming out of battery) of ~2A. But at dead stop, current drain is usually ~0.8A. So don't think that you are not losing energy at all, even tho is not that significant.

About how to get to no arrow, yes it does take a little practice. It also depends on ICE temp, ur a/c setting, speed, the slope, and other factors. AlphaTeam, don't be discourage if you can't get no arrow on MFD, you might not have the right conditions.

 

I also drive in exclusively mountainous terrain. My commute takes me from Vegas (2300 ft MSL), over several passes and valleys (0-5500 ft) back to 2300 ft MSL. My lifetime avg is 45.5 MPG. No doubt it could be higher, but the battery capacity cannot store most of the regenerated energy as as I coast downhill. Therefore much of the energy spent getting uphill is lost as I coast downhill with "B" selected and the battery full. Bummer, but what can you do besides get some bigger batteries?

This problem is magnafied on trips to Mammoth with 10000 ft elevation delta. Uphill I usually get 31-33 MPG, but on the return I cannot capitalize on the potential energy so I end up with a 40 MPG round trip instead of 50+. On the uphill runs my hybrid battery runs out right away, and the car can barely pull it's own weight by the time I get to 7000 ft. This will probably wreck my hybrid battery much earlier than 150,000 miles.

 

I also drive in exclusively mountainous terrain. My commute takes me from Vegas (2300 ft MSL), over several passes and valleys (0-5500 ft) back to 2300 ft MSL. My lifetime avg is 45.5 MPG. No doubt it could be higher, but the battery capacity cannot store most of the regenerated energy as as I coast downhill. Therefore much of the energy spent getting uphill is lost as I coast downhill with "B" selected and the battery full. Bummer, but what can you do besides get some bigger batteries?

This problem is magnafied on trips to Mammoth with 10000 ft elevation delta. Uphill I usually get 31-33 MPG, but on the return I cannot capitalize on the potential energy so I end up with a 40 MPG round trip instead of 50+. On the uphill runs my hybrid battery runs out right away, and the car can barely pull it's own weight by the time I get to 7000 ft. This will probably wreck my hybrid battery much earlier than 150,000 miles.

 

heh... alot of these numbers just go over my head...my reaoduts are in liters and kilometers.... metric was introduced in the 60s....it seems the US is a bit slow to catch on

 

Just wanted to add my mileage so far. I only have around 250 miles so far on my 2006, but I'm averaging around 50.5 mpg so far. Not too bad considering I'm driving my Prius just like any other car. No special techniques to maximize mileage. I'm impressed. I'm sure if I tried I could get quite a bit more, but I'm really not interested in driving 55 on the interstate and coasting for miles and so on. That 50.5 mpg is with an average speed of 75-80 on the interstate. In the city, I drive just like I drive my SUVs. So far I'm very pleased.

EDIT: BTW, Florida is VERY flat, and pretty much the only hills I drive are interstate overpasses.

 

Congrats on your new 06! Glad you're enjoying her. BTW -- I thought the first several hundred miles were supposed to be at lower, varying speeds. 75-80 seems pretty high for out of the dealership.