My Mile/MPG Break Even Point - Volt vs. Prius

It's silly to use MPG(e) as a comparison since it doesn't consider what is really critical to a consumer. Price is what matters, and the MPGe standard ignores it with the assumption that all fuels are equal. Electricity pricing across the country isn't anywhere near as standard as gasoline pricing, either.

For anyone doing the comparison of cars, cost per mile under electric and gas needs to be calculated at today's rates for each as well as their expected driving pattern.

 

Price is supposed to be excluded from the measure of efficiency.

That's a factor outside the realm of how the system itself operates.

Think of it this way. If two different approaches cost the same, by what means would you know which consumes less energy?

 

It's not an either/or subject.

The provision of standardized measures is seperate.

Pricing can also be provided, to further help consumers with their purchase decision.

 

Without knowing quantitative energy usage, cost per mile for one person is not meaningful for another.

If you know energy usage, anyone can calculate their cost by plugging in electricity and gas cost.

I don't like MPGe either because it does not consider upstream (fuel production) efficiency. 100 MPGe = 33.7kWh/100mi

I like how PiP reports both fuel usage.



You know how many miles I went with how many kWh of electricity. Ditto for gasoline. You just need cost of kWh and gallon of gas to determine your costs per mile per fuel.

Anyone can get their specific numbers from those 4 core values.

 

Or emission.

 

Higher efficiency means less waste which translates to cleaner emission and lower cost to operate and to clean up.

Government incentive and free fuel can be monkey wrench and distort the view.

This thread can be summed up as, "I get free electricity so my EV miles are cheaper than my gas miles."

Or "The extra energy Prius gained by higher gas engine efficiency can be cancelled by the free electricity I get in my Volt."

 

That's an important fact I forgot to mention!

 

Now I am confused. I thought it was leather.

 

Sorry, but to draw a conclusion, all the factors at play should be taken into account.

And isn't the point to give enough detail so others can figure out how their situation will actually vary?

 

Did you get a full charge? It said you went 50 miles with 18 kWh of electricity. Perhaps mostly downhills?

But then your gas mileage was very poor. Mostly uphills with it perhaps.

 

Justin; I am with you and John; you are right, but following your advice requires us to use a process that is broken in my opinion. We don't use the energy content of gasoline to determine our efficiency so why do we do it with electricity?

Again, I use cost per mile because its an easy relationship between my new and "somewhat" confusing situation and their very familiar one. I agree its not an "efficiency" thing at all. For that, I use miles/kwh but only with OTHER EVers because it has no relationship with gassers.

MPGe kinda reminds me of first year Physics. The goal was to learn the formulas and basic relationships so "real" world elements were ignored at first. This was wind friction, terminal velocity, etc...

 

You are getting old, Justin. Time was, you would never post that cynical a picture no matter how funny.

I, of course, thought it was hilarious.

 

Change free to lower cost and you're right on. In F8L's case EV miles are about 3x cheaper than gas miles, even if he pays an average US market rate. EV miles are also cheaper on the PiP or any other EV, it's not just a Volt thing.

The main point I failed to make originally was that multiple potential charges per day change the "break even" point significantly higher than the frequently quoted 70 mile day. Many charge twice per day, some even 3 times. This impacts the rule of thumb greatly.

This misunderstanding kept me out of any EV for a while.

Sorry for any feathers ruffled.

 

The topic of how to properly present data has been brought up many, many times.

These categories are what came about as a result of those countless discussions...

 

^^
John,
Can you clarify the 2.75 kWh/charge shown on the right side of your picture ?
By calc I get 3339/1138 = 2.93 kWh/charge