Here is the comparative formulas for operating a PiP in all gas vs. all electric

I'm pretty sure that it takes 3.3kwh for a full charge, and most people are seeing just under 3 in real world. Electricity is .06/kwh here in the PacNW, and regular gas is $3.90/gallon, I drive about 10k miles/year. So using those figures and your formulas:

3.9*(10000/50)*1=$780

3.3*.06*(10000/12)*1=$164.99

$780-$164.99=$615.01/year savings (best case)

 

EPA said PiP need 3.2 kWh and 0.3 gallon to go 25 miles. That's a full charge plus some gas.

PiP has 4.4 kWh pack. It uses 62% (85% to 23%) so it uses 2.73 kWh. If we add 15% charging loss, we also get 3.2 kWh.

Compare Side-by-Side

 

There's a simple way to computer this. Most people use cost per mile to make comparison.

PiP cost per mile in all electric = (cost/kwh) * 3 / 15

Standard Prius cost per mile = (cost/gal) / 55

Based on where I live, the difference is .05/mile (advantage to PiP). Since I only could charge once per day and I drive more than 15 miles per day, the most I would save is 0.75/ day which is equal to $274/year. It will take a little more than 9 years to recover the higher cost of PiP. If you could charge twice or more a day, that would be the best especially if you could get free electricity at work.

 

I have calculated 12 months. Mine is at 54.5mpg. But I guess you could use 50mpg for overall

 

Last 16 months ICE only 52.6 mpg. includes driving car home from dealer.
Since 4/7/12 Ice only 56.3 mpg. excludes drive home from dealer (1475 miles).

 

You have to know that I don't go on highway too much daily. Most of the time, I'm under 55mph. I do hit the highway to work but that distance is short. I do take long trips and there's where I go 65mph to 70. But I only do long trips a few times a year.

 

Vulcan....I'm sure there are a lot of tricks out there to get max MPG. I'm not into getting the max, I'm just into getting the great MPG. I only follow a couple of basic rules. Use the ICE when power requirement is high. Use the battery or no battery when power requirement is low.

For example, if you know there's a hill coming up, you want to press harder on the accelerator to get your speed up using ICE. This is a situation where battery is not right for the job.

If you're in a busy parking lot and you're trying to leave, you would want to turn on the EV mode.

When you're just getting on the highway, you would want to accelerate using ICE and once you're at the cruising speed, back off on the accelerator. Highways are not perfectly flat so if you see a decent coming, you could back off the accelerator and let the Prius glide using battery.

I have a standard Prius so I don't know if this is something you could do with the PiP.

 

PiP tracks the miles you operate in HV mode and the gallons used. Below is mine. 1,572 miles with 28 gallons = 56 MPG.

 

Basically, a PiP is a standard Prius with a bigger battery and charging circuit allowing you to add electrical fuel from an external source. Unfortunately, the electrical fuel tank (battery) could only hold enough charge to go about 15 miles. Therefore, if your daily commute is 17 miles or more, it would be wise to try to maximize the potential of each type of fuel you're carrying. There's nothing stopping you from trying to climb a hill using electricity but that wouldn't be efficient. It is better to save that electricity for cruising or driving at low speed.

 

first of all - kudos on doing all the above - looks impressive !

BUT as mentioned before $3.30 gas isn't the norm - I'd use at least 10% higher and you know CA is 20%
that's a big difference in outcome right there
as is a better range than 12miles. I'm in the Boston area and even when it was in the 30's I exceeded 12, currently 15-16 actual.
Plugging in those numbers I'm getting savings of $800 and free charging has been netting me another $10/mo = $900 annually

 

Interesting what you come up with once you start doing this.

First, it works with different units too. In the UK, even though we still think about miles per imperial gallon, we have bought petrol in litres for about thirty years now, so (despite my Fuelly sig) I'm trying to wean myself onto miles per litre; 15.9 from the one reading I have so far between full fills. Cost in £ sterling, obviously. Range per charge - I get about 12 m at the moment, but that will drop in the winter. However, I also get nearly one in two charges included in the price of my parking, so I've used 20 as my range per charge I pay for (probably conservative). Petrol cost me £1.33 a litre this morning (I make that $5 - and I had gone to the cheapest on my route, the average is more like £1.37). With a .68 HV percentage, that gives me:

*Yp = 1.33 x (12000/16) x 0.68 = £678.30
Ye = 0.51 x (12000/20) x 0.32 = £97.92

Compared with no electric mileage, that looks like a saving of £221 a year, or $333, which is nice, and with our fuel prices more than I'd get in the US, but not a massive amount compared to the cost of the car. However, that HV mileage is almost entirely at motorway speeds; even in a standard Prius I surely wouldn't have been able to get that sort of economy from the third of my driving that is mostly stop/start? I also need to get a cheaper electricity supplier; I can probably reduce that a bit.

Plus, it's interesting to compare with the ten year old Mondeo I traded in for the PiP. It averaged 40 mpg (imperial), so 8.8 per litre. So total cost for the same mileage would have been £1814; I'm saving about £1040. Plus I save the £250 annual car tax on the Mondeo, and probably about £200 on the bits that were needing replacement each year. Since I bought my PiP second-hand, with the first year depreciation hit already taken, the savings I am making are probably matching the value I am losing in depreciation already - and I couldn't have kept the Mondeo running much longer without expensive bills.

*Yp because I fill up with petrol, not gas...

 

Vulcan - I did a similar "Prius vs PiP" calculation before and it's fairly straight forward since the PiP is already a Prius. It'd be much more difficult if you were comparing two totally different cars. Many posters swear that the PiP can still provide better mpg after the battery has been exhausted. However, for the sake of simplicity, we can assume that the PiP is going to behave like a standard Prius when in HV mode. IMO if you're just looking at the cost and benefit and nothing else, the PiP is most likely not worth the money if you could only charge it once per day. The whole idea behind the PiP is that you get a bigger battery and you could charge it using an outlet instead from the ICE. Charging the battery from an outlet is much cheaper than charging from the ICE that burns gas. Therefore, if a person has the opportunity to charge often, he'll be using cheaper energy to run the Prius.

I could see the PiP being a great car for a home maker who just using it to drive around locally all day long picking up and dropping off kids at school or at other activities. This kind of driving pattern would allow opportunities for frequent charging between trips. People who could charge at work and get free electricity should also consider getting a PiP.

 

Do other people really see 3.2 kwh for a full charge...when you are driving in EV only for days at a time? Charging losses have nothing to do with this. I drive in EV only Mon-Fri most weeks.I charge at an L2 ChargePoint at work, which reports the kwh used from the wall. When I drive to where the battery just shows 0.0 miles remaining, but DID NOT drive with the ICE and drop the batteru SOC even more), the most I can charge is about 2.6 - 2.7 kwh. I get a displayed 14.4 EV miles with this...and usually get about 15 miles of actual range. A few weeks ago I carefully drove to 0.0 miles remaining several times and did these measurements.

Mike