Can the Prius MPG be improved?

I can't speak to your exact scenario w/o more info but for all I know, the ICE might be cold and providing requested cabin heat. See http://priuschat.com/forums/gen-iii...mileage-gets-worse-in-winter.html#post1411488. Or, the ICE is cold and is still warming up (i.e. you're not past stage 1a or 1b, see http://priuschat.com/forums/knowled...perating-mode-availability-reference-aid.html).

How fast are you going when you observe the above? Going up or a down a grade/hill? How many minutes and miles have you been driving by that point?

As for "increase the Electric Motor use, to put less strain on the Gas Engine and improve its MPG", on the non-PiP, all the energy ultimately comes from gasoline. There's no free lunch.

Perhaps this thread really should be moved to the Gen 2 FE area and isn't a PiP question.

 

It's likely best to stay with the default battery usage programming, and I think Toyota has taken a responsible, conservative approach: not overtaxing the battery.

On the other side of the fence, Honda's first and second generation Civic Hybrids have a relatively small battery with high demands: and a higher failure rate.

 

Because the Prius isn't a plug-in. All charge in the battery ultimately comes from the engine, whether from engine through the motor to the battery (normal generation) or from engine to wheels to motor to battery (regenerative braking). There are energy conversion losses at all stages and more when it draws charge back out of the battery to turn the motor.

To be worth using the electric motor it has to be a situation where the additional losses accrued charging and discharging the battery are outweighed by the efficiency of the electric motor over the engine. In the Prius this means trying to keep the engine in a narrow, efficient band and have a slow draw of charge from the battery. The basic idea:
- At low demand using the engine is inefficient and the motor is efficient so it's better to use the motor and turn the engine off
- At middling demand using the engine is efficient and the car can use small amounts of assist from the motor to keep the engine running steadily. It can also keep the engine running steadily and efficiently and use excess power from the engine to charge the battery.
- At high demand the car uses the engine more but will throw electric assist in the there to help provide power. The Prius engine is "Atkinsonized" and has reduced power but is more efficient at normal levels of demand. It can use electric assist to make up the power deficit.

The car's programming blends the engine and motor to try and make the car operate as efficiently as possible. It's not perfect and good hypermilers can "beat the computer" but overall it does a pretty good job.

 

I see it about the way ItsNotAboutTheMoney does. The more I learn about the Prius the more respect I have for the work of Toyota engineers.

Of course, Hobbit has done some remarkable stuff and published it here:
Hobbit's techie-rants It is not all new but it is all interesting.

We can always benefit from better driving skills.

 

I should add that rapid draw of charge from a battery shortens its life, which is another reason to avoid it.

Also, just in terms of efficiency even in the Plug-in Prius it will be better to avoid large draws, although it should tolerate them more. The Prius has EV mode to allow the driver to tell the car to favor use of the battery:
- In the regular Prius the main reason to favor EV is that the driver is in a situation where the engine would be run particularly inefficiently, such as avoiding the normal engine warm-up when moving the car.
- In the Plug-in the main reason would be because the driver knows they can complete their journey on charge from the plug

If the programming assumes that the driver selected EV mode for the reasons above it would make sense that the Plug-in Prius will provide more assist in EV mode than in a regular Prius.

 

IMHO you'll get better results with non-ECU mods like LRR tires at higher psi, grill blocking and hypermilling.

As isn't about money said it is not necessarily efficient to discharge battery and then charge it again from ICE; it could be if ICE is running at minimal load/high pumping losses but not when accelerating.

Also if you want to switch to EV mode at cruising speed all you need is to blip accelerator to shut down ICE.

 

In a way, it is like cruise control. Using cruise can improve fuel economy. Keeping engine load at a constant output, as the cruise control does while on a flat road, is an effective hypermiling technique. Cruise control, unfortunetly, is reactive. It doesn't see up coming hills, turns, etc. and can't plan for them. So you will likely use more gas on a hilly or twisty road using it than your own foot. There are large hills on my commute I can get up without having the transmission downshift. With cruise, the car will do so and early, which instantly drops the mpg by 5 mpg.

During winter, the Prius always had a full SOC when a neared home, because the engine was running more for heating itself and the cabin. I thought of getting a small 12 volt heater to try and draw it down some. Yes, an inefficient use of the electricity, but I would than have more reserve of regen braking, like in the warmer months, when I got off the expressway.

Someone has done what the OP asked for the original Insight, called MIMA, or manual intregrated motor assist. It isn't a simple EV switch. MIMA let's the driver override how much assistance comes from the motor. In the OP's situation, he can tell it to use a little more or go full EV(as much the Insight 1 could). In situations of steady driving, like on the highway, he could then tell it to use little to none. For most it's just a gimmick, but for a hypermiler it can mean big improvements. MIMA Insights have held mpg records.

I highly doubt we'll see such a system for the Prius. The HSD is more complex, and thus more daunting. Plug-in kits are less invasive to the system than would this require. Plus, as a whole, Toyota owners seem less likely to undertake such heavy modifications than Honda owners.

 

One surefire way of greatly improving your mileage is to do 25mph everywhere, on trips too. Seriously, there are definite limitations as to what the car can do, these are inherent, you cannot get around them. However, you can see an improvement by just doing the speed limit. :cheer2:

 

We know what you are saying, and your desire is being fulfilled via the PHV Prius.
Any change in programming on a standard Prius, for more Electic assist, would result in LESS MPG. The Toyota engineers got it right.
You do have a control to increase your MPG, it's your right foot. Reduce how much and how hard you press the gas pedal and your MPG"s will go up.
Learn how to glide. Any Prius owner that doesn't understand or doesn't take advantage of the glide capability is missing the best built in feature of the car, that increases gas mileage.
The change needs to be in YOUR ECU, not the car's.

 

I don't think that's entirely true. The regenerative braking of the Prius is designed to mimic engine braking in a non-hybrid. Controlling the accelerator so the Prius glides is a way to overcome this engine braking mimicry. But if there were a mode where regenerative braking only occurs when you hit the brake pedal and the Prius glides when you let off the accelerator, gliding for higher mpg would become much easier.

 

Here's a thought inside the box......slow down. The amount of wind resistance you see at 70 mph has a definite impact (detrimental) on fuel mileage. If you slow down to 60 mph, you'll see a remarkable improvement in MPGs.

Instead of worrying about the engineering of the car, worry about parameters you can control, speed, distance traveling between you and the car in front of you, braking, tire inflation, unnecessary weight (both in the car and around your waist line ), use of the HVAC system, trip management to name several.

At least you can control these things. Besides, using the battery, ultimately, wastes gasoline. Others have pointed this out....

 

I'd rather modulate the gas pedal to control coast vs. glide, that's where my right stays most of the time anyway. Rather than module the brake pedal for coast vs glide. Glide is a forward momentum movement, and I want to control that with the accelerator.
I want the car slow down when I let off the gas, and speed up (glide) when I touch the gas.
The car is genius the way it is.

 

As Cyclopathic said, you can put the car into EV by just releasing the throttle and re-applying. But when you do that frequently, especially when electric motivation requires pushing the Hybrid System display bar near the median, you will eat up the charge pretty fast. When I see that situation I'll purposely step a little harder on the gas, to restart the engine. In short, you don't want to push it.