Prius Plug-in Versus Volt: Which Costs Less to Drive?

[usbseawolf2000]

PluginCars posted this article without details of the cost of fuel and the calculation. The graph is also confusing because it started out with 15 miles interval and then jumped to 30 miles interval. That interval change in X-axis created an illusion of an inflection points at 30 miles mark.

So I decided to create my own graph. The spreadsheet with the formulas are available here if anyone wants to review.

For the graph below, I am using national average price of electricity and gas. The assumption that only one recharge was made. If you do multiple recharges for every 15 miles, PiP will have an edge.

Electricity	$0.11 per kWh
Regular Gas	$3.5 per gallon
Premium Gas	$3.8 per gallon
PiP kWh	3.6 kWh per charge
Volt kWh	12.9 kWh per charge
PiP MPG	49
Volt MPG	37

For the graph below, I am keeping the price of the electricity at 11 cents per kWh and I increased the gas price to $4.5 for regular and $5 for premium.




For the graph below, I kept the gas prices the same as the first graph. The price of the electricity is increased to 19 cents per kWh.

[Roadburner440]

USB if it helps at all I would adjust the volts kwh down from 12 to just a tad over 10 to maybe 10.5 (that is what I have observed to be usable), and I would also adjust the fuel mileage down to the low 30's.. I personally have seen 28-32mpg motoring about town. That is from my own personal observation, and hopefully it will give you some real world data instead of their best case scenario numbers. Granted the actual range is somewhat more than indicated, but it is about to go down into the 30's for the winter. That article also backs up my previous observation I made in another thread that it only takes about 70 miles to make the Prius a better option. I assume it will be less for the PiP seeing as my own 70 mile figure is based on our 2011 Prius which we regularly achieve 51-54mpg in and is not a PiP. I think the PiP cost will wind up being lower than what the graphs even show since we already know all the tips/tricks to getting good mileage around here, so will be interesting to see what the real world numbers for the PiP look like when people start getting them.


Taken after fully draining the battery from a full charge in 1 drive. Is why I doubt the 12.9kwh hour estimate. That would give me another approx 7-10 miles of range, and I would greatly appreciate that.

[john1701a]

Originally Posted by Roadburner440

USB if it helps at all I would adjust the volts kwh down from 12 to just a tad over 10 to maybe 10.5 (that is what I have observed to be usable)

The point is to illustrate overall consumption, including the overhead of the charging process itself. So, you want more than just usable listed.
.

[Roadburner440]

True John.. I really need to get one of those meters to plug the charger into to see what the draw is for the charge and battery conditioning.. I keep forgetting about that. I pay a flat rate for the garage at the moment that has its own seperate electric so not really sure what the overall draw of the car is personally. Will certaintly be finding out next month though. Doing a little more digging USB's original figure is correct, so I apologize. I do sometimes forget the thing is a tad more complex than say plugging in a cell phone.

[usbseawolf2000]

Yea, I am using the official EPA figures to compare. When we have PiP's EPA numbers, I will update the graphs. Right now, we only have the info from the production announcement and data from the prototype.

[hill]

Originally Posted by Roadburner440

True John.. I really need to get one of those meters to plug the charger into to see what the draw is for the charge and battery conditioning.. . . . . . snip.

EV'rs can tell you that as a general rule, there's about 10% loss going from AC wall power, to DC battery charging, to storing the juice. Example from personal experience; although I'm calculating out 5.5 miles per kWh, I'm actually at 5.0 miles per kWh at the wall. Exactly 10% loss.

[Corwyn]

What are you using for miles per kiloWatt-hour?

[hill]

A Fluke, and the Leaf's odometer. Pretty straight forward.

[usbseawolf2000]

Originally Posted by Roadburner440

That article also backs up my previous observation I made in another thread that it only takes about 70 miles to make the Prius a better option.

If you take account of the gas price difference between regular and premium like in my graph, the crossing point is the 50 mile mark.

[gwmort]

Why is the prius cheaper to run in CD at 87 mpge than the Volt at 94 mpge?