EV %, mi/kwh, avg speed

Toyota recommends 5 gallons a year to mix up the gas. But I think using gas that has no ethanol additives will help. It will help for longer storage, less water build up. Better for the engine. Also when fueling up use a gas station that meets Top Tier standards engine cleaning detergent additives. Non Top Tier gasoline causes 19 times more deposit then Top Tier brands after 4000 miles. Such carbon deposits are known to reduce fuel economy and will have a negative impact, particularly on newer vehicles. To find top tier gasoline stations go to 404 - Page Not Found | TopTier Palletizers
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Concern over gas shelf life was a one major reason the gen1 Volt required premium fuel.
Turns out a modern fuel system is sealed well enough that the concern was over cautious. The Prime has a more frequent fuel maintenance cycle than the Volt; it is going to fire up the ICE more often even if all your miles are EV in order to use up old stuff in the tank. IIRC, every 200 miles of EV is the setting.

 

What is the minimum gas use per episode ?

 

Let me rephrase:
The Volt has less frequent fuel maintenance cycle than the Prime; it is going to fire up the much less efficient ICE less often trying to reduce pollution.

 

I need to state what I said. The two hundred mile interval is for engine maintenance. There posts by those with more knowledge elsewhere in the Prime section. it should be long enough to get everything well warmed up and oil flowing everywhere. It is improved over the PiP, which went 124 or 125 EV miles between events.

Anyway, no matter which model or whether engine or fuel maintenance, I don't think people need to ponder which gas to use for longest shelf life.

Toyota is just being much more conservative over engine protection than GM is. That could be spun as better, but Toyota's more conservative also means using a less efficient 4 speed automatic in the Yaris and base Corolla.

As for the Volt being less efficient in hybrid mode, it is. The prime is about 19% more efficient than it, and it burns a half gallon more gas over 100 miles. The 2wd Silverado with 5.xL V8 is 20% more efficient than the 2wd Tundra with 5.xL V8. The Tundra burns 1.1 more gallons over a 100 miles; 1.7 more gallons than the 2017 hybrid Silverado. Which segment do more Americans buy?

 

And even less efficient in EV mode, which at least to me is surprising*

*There are many ways to calculate this but the simplest is to compare MPGe's
Prime is 133
Volt '17 is 106

= 20.3% less efficient

 

And emits less CO2.

 

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With dual motor use, the Prime can produce 91hp in EV mode. For the Volt, it is 149hp. There can be efficiency loss for performance. The extra 500 pounds for the bigger battery doesn't help.

About 4.5kg less per 100 miles, and the Silverado(non-hybrid) emits about 9.8kg less than the Tundra over the same distance.

The Prius is King when it comes to efficiency.
The majority of us get that. What many don't seem to get is that being King means the Prius is the high end outlier on the efficiency curve.
Others should and do aim for the Prius levels of efficiency as goal.
Putting them down for not matching the Prius' efficiency is a disservice to the efficient car segment.
The Volt gets a mere 42mpg combined in hybrid mode on the EPA. Equivalent ICE cars, that sell in greater numbers than the Prius, get into the mid-thirties at best. The Volt saves as much gas over them in 100 miles as the Prius does over it. The 53 miles of grid energy helps reduce gasoline use further.

The average MPG of a new vehicle sold in the US is 24ish. Not everybody wants to drive a Prius. Would you rather they bought something that got 42mpg? Or are you fine with them only getting 35mpg, 25mpg, 20mpg, or less instead?

I only brought up the Volt and mentioned its engine/oil maintenance interval as illustration for those thinking of needing high end gas or additives because of low fuel use that this isn't a concern you need to worry too much on. Not every mention of the Volt, diesel, or other hybrid is because the poster wants to get into a pissing match.

 

What these numbers have to do with the EPA rating?

 

The Volt has lower efficiency in EV operation than the Prime; a lower EPA rating.
There are many factors, but having performance potential from the motors than Prime, including a higher top EV speed could a partial explanation for the difference. Like a more power ICE, the motors may not be operating under their most efficient load on the EPA test.

 

A reasonable explanation for HV mode, but not for EV mode

 

Electric motors have speeds and loads at which they are more efficient at producing power for the energy in. Just like ICE engines. If your engine/motor spends more time operating at that more efficient point for the test, then it will get a better rating with all else being equal. The dual motor Teslas better better range and ratings than the single motor models, and they could have near identical power and torque ratings.

 

Electric motors do have power curves, but they are no where near as pronounced as ICE for usual driving conditions and their curve shapes are quite different.

The Tesla is a poor example for two reasons:
1. Tesla was mitigating the power curve of an induction motor, not the PM motors used by Toyota and GM
2. The improvement seen in the dual motor Tesla was related to high load conditions, exactly the opposite of your presumed Volt motor inefficiency from low partial power.

Some of the higher energy consumption of the Volt compared to the Prime is explained by car mass, car Cd, and perhaps tire choices. I've never been interested enough to calculate the differences and really only have a memory of this point at all because the Volt fans were POSITIVE that their favored car would thump a Toyota PhEV in EV efficiency. You know -- serial drivetrain, blah blah blah. Toyota are the kings of efficiency, period.

 

Unlike ICE engines, AC motors have quite a flat efficiency curve of over 90% efficiency from 30% to 110% load, typically 45% and 100% loads have same efficiency and the maximum is at about 70%. Difference in efficiency between 70% and 45% loads is typically 1-2 percent points.

 

If you had ideas for the lower efficiency, then why did you claim to find it surprising in an earlier post?

 

I distinguish between efficiency and consumption rate. I think *some* of the consumption difference is explained by the differences I mentioned earlier, but that still leaves a drivetrain efficiency difference I am surprised Toyota matched, let alone beat compared to the Volt.

 

If we took the motors out of the Volt and Prime, supplied them with the same exact amount of energy, something well below their max input, would they produce the exact same amount of force at their shafts?

 

I cannot tell between the Volt and the Prime, PM synchronous AC motors are typically a bit more efficient than induction asynchronous motors and at a wider range of loads and voltages, and Toyota invested a lot in improving efficiency of their PM motors, don't know about the Volt.
A 100 hp 3 phase 460V induction motor producing 50 hp will consume ~60A, similar to a 50 hp motor at full load.