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How to Maximize Your MPG

12K views 20 replies 15 participants last post by  DCFlyer  
#1 ·
Now that this forum has tough me how to extend my battery rang by 25%. It's time to learn how to maximize the MPG when forced to drive using the ICE.

Please post what works best for you and what speed is the works best when using the gas generator.
 
#2 ·
It's mostly the same things - slower speeds, less HVAC, slower accleration/braking, more coasting. Although it hasn't been proven, the most efficient speed in extended range (in fan only) is probably in the 35-40 mph range, since this is where the car starts operating in power split instead of series.
 
#3 ·
More energy needs = lower mpg.
Faster = more horsepower needs = lower mpg.
More internal "bits" turned on (heater, AC, headlights) = lower mpg.

If you want to lower your 65mph speed to 60mpg, you may gain nearly 1mpg on a steady-state highway drive. But that also could be slightly dangerous in a busy highway situation where maintaining speed with your lane is important. Is it worth adding slight risk by trying to get another .5 mpg out of the car? Probably not. Just drive it - it's a regular old car (that just happens to have an electric motor and really good effiiciency).

The best way to get better mpg in all conditions is to keep your tires inflated well - 38psi or slightly higher.
 
#4 ·
Efficient driving is about the same EV vs ICE, with one exception. Sitting at a stop sign in EV costs you very little, sitting at a stop with the ICE will use the excess power to charge, but that is still a 15% loss.

So if you are a trip long enough to need ICE, save some EV range (hold if you have a 2013, Mountain mode) for the stop/go of the city. Mountain mode can save 10-15 miles for EV, but you want to use it BEFORE you get to less than 15miles of EV left, if you turn it on after you have used the battery it will work much harger to generate the EV buffer and will cost you in range.

As for either case, keep the speed in check, keep the tire properly inflated, use Cruise control, keep is smooth at stops/start.
 
#5 ·
I just got back from a 1000 mile trip and had a chance to put the CS mode through its paces. Most of it was highway. However, during the stop and go parts, I noticed if I accelerated very lightly (egg between accelerator and foot), the ICE would come on just over 20 mph in most cases. If I accelerated a little bit harder (enough to keep place with other cars, the ICE would not kick in until about 40 mph in most cases. This isn't 100% true on all occations. I am guessing it depended the SOC and other variables.

It did get me wonder if there is some time variable from a stop to get you up to speed before the ICE kick in where the ICE could run at its most efficent level? Since it didn't happend all the time, it may just have been coincidence.
 
#6 ·
That's interesting - my experience (and expectation) is the other way around - that if you accelerate lightly the engine comes on later. I believe from what I've seen that within the CS SoC window the car mostly decides engine operating conditions based on power demands rather than SoC - if you come off of the gas completely in L at ~50 mph or less for more than a second or two, it'll shut the engine down no matter where it is in the SoC window (or if you apply enough brake pedal to equal L feet on floor.) Engine start can be delayed by higher SoCs - as in you started braking to a stop when it was near the top of the window anyway, and so it had a bunch of battery power to use.
 
#7 ·
On one long trip this past summer I tried running in mountain mode rather than just letting the car run down to cs mode. I found the car didn't rev up as high in mountain mode as it did in cs. I was driving on low rolling countryside. I've found, in cs, the car would rev up higher on the hills than it does in mountain mode. Now around here we only have short hills so maybe with more vertical, mountain mode would rev up just as high, but for long trips I use mountain mode now. I don't know if it is any more efficient but I've found it a bit quieter in my terrain.
 
#10 ·
Now that this forum has tough me how to extend my battery rang by 25%.
Was going to start a new thread asking basically what you've learned. want to share?
My question is if I'm driving up a steep hill that is 5 or so miles and going 70 on the freeway which mode should I use? and does it depend on how much juice I have left? What about going down that same hill? How early should I switch modes before/after the incline?
 
#11 ·
1. Use the NAV to find the shortest path to my destination.
2. Stay off the expressway it kills the battery
3. Drive in "L" it seams to help.
4. Slow starts (Use the green ball on the display.
5. Use the gas petal in "L" to slow down as you get to a red light.
6. If you are going to have to use gas use it on the expressway.

Went from 42 miles range to 52 miles range.
Since my commute to and from work is less than 50 miles I now never use gas.
That is not till the winter gets here.

You will have to ask your question about how to get best mileage on large hills.
 
#13 ·
A lot of this is dependent on how fast you normally drive on the freeways. Staying as far below the speed limit (while still keeping pace with the flow of traffic) can add up. A 5 mph difference doesn't seem like much, but it can add several miles to your electric range. Every 5 mph increment over 50 mph will cost you a decent amount of range. Also, if you can draft behind a large truck (at a safe distance, of course), you'll benefit even further.

In terms of hills, that's tough. For ICE cars, you can do "target mpg" driving, where you slowly decelerate, while maintaining your highest mileage possible, but ICE and EV cars act very differently (e.g., pulse and glide doesn't work on an EV). You might just have to watch your uphill speed, and try to recoup as much as you can on the way back down.
 
#14 ·
If you try to avoid touching the brake pedal, that mindset somehow changes driving style in ways that dramatically improve mileage IN ANY CAR.

I once drove a Grand National that in full tune (600hp+) and driven normally got a wonderful 11mpg on the street using 115 octane avgas. Expensive, though it could embarrass almost anything. But when I drove as though there was an egg on the brake pedal, mileage almost doubled. Of course, when the hammer went down, the turbo spun up, and all 7 injectors (yes, 7) were flowing, the gas gauge seemed to snap to E. But without doubt, I could drive on the streets at about 20mpg by avoiding the brake pedal.

That seems to work well with my Volt, whether on battery (mid 40s) or ICE (~40).
 
#15 ·
What notaguru says is right, and I think that the regenerative braking on the Volt lulls some people into a falls sense of... economy? Anyway, you can never fully recoup what is lost (I think the Volt's regenerative system has been rated at about 70% efficient, which is very high), and the difference in energy between accelerating from 0 to 40 mph and regenerating from 40 to 0 mph is far more than the energy required to maintain forward motion at 40 mph (staving off rolling resistance and drag). If someone could find a long enough and flat enough stretch of road (no bends, turns or elevation changes), they could probably drive a Volt almost 80 miles or more on a single charge. Someone was able to do a little over 70 miles on flat ground, and that was in > 100* temperatures with directional changes.
 
#16 ·
Our brilliant car creates all sorts of opportunities, and we have to learn to exploit them. It's not just loss of kinetic energy to heat -- regen handles a lot of that.

Even more important, consider what happens to driving style when the brake pedal "doesn't exist" in your mind... You plan ahead more, take corners more aggressively (preserving energy), and in the Volt you use L and do virtually ALL your stopping with regen, etc.
 
#17 ·
The egg on the brake peddle is great advice notaguru! It also makes you a more aware driver as well as saves your charge. On flats I try to coast up to red lights in D with the intention of not having to stop. That means coasting from well back, if traffic permits it. If it is busier on the road I will keep up with the flow a bit more and run in L trying to avoid using the brakes until the last minute or just enough to warn someone behind me that I am slowing. In my area if you do the speed limit most people have passed you and are ahead of you anyways. Speed limits are plenty slow in our area so I rarely drive below the limit. I think I would be shot if I did!! LOL
 
#19 ·
3 very important data points:
1) ICE is more efficient when the load is high and the RPM is low.
2) ICE is most efficient when it is off.
3) It is not an efficient process to use the ICE to recharge the battery.

These are the main reasons why "pulse-and-glide" on a Prius will improve MPG a lot. Essentially, you use the ICE ONLY at full throttle to accelerate the car (1). You then glide with the ICE off and allow the speed to reduce naturally (2). You can feel it clearly that by depressing the accelerator slightly, you could disable regen and just glide. You then accelerate again using ICE ONLY and repeat the process. Notice that the battery is not used since any battery power used will have to be replenished later with the ICE which is an inefficient process (3).

On the Volt, however, I don't think there is an equivalent of accelerating with ICE only since I think the ICE connects DIRECTLY to the wheels only when cruising. And, also, it is not easy to glide without going into regen and the car starts to slow down. I have not spent enough time in extended range mode to try different methods. I would think driving at a constant speed and let the software handle it is best.
 
#20 ·
I've had my car for a whole week and I'm averaging about 42 - 44 per charge. I live in San Diego where freeway cruising speed is at least 70 MPH. A few hills and canyons and moderate temps.
1. I drive in L all the time and take advantage of regen whenever possible
2. When on the freeway and it's not stop and go and put the car in HOLD mode and keep a steady speed
3. AC is always on ECO unless it get's brutally hot. I always pre-cool the car while it's plugged in
4. I accelerate and slow down normally, no eggshells on the go pedal
5. No extra junk in the car - minimizing weight

Actually the only time I get less than 38 miles per charge is when I'm driving more aggressively in SPORT mode, basically taking friends out for test drives.

Great car so far - just gotta get the fix for the wind buffeting when the windows are down.
 
#21 · (Edited)
I don't claim to be an expert, and I've only had the car a month. I get a little more than 45 MPG on ICE at this point. For some reason my overall average of 43.06 puts me in the 97.6 percentile for MPGcs on Voltsats (#45). Virtually all of my ICE miles are highway (I use Hold mode on long trips). It seems leaving it in low to maximize regen might be helping. I notice my MPG really starts taking a hit above 65 MPH.