Why Toyota is not selling electric cars

Since MPGe includes from wall to wheels, you need to measure the electricity used at the wall.

There are various ways of doing this. I measure the power drawn from the outlet with the eGauge power monitoring system. On a 110 outlet some people use a Watt meter. Others just estimate based on the estimated charger loss. As I recall, it is about 15% loss charging at 110V, about 10% charging at 220V.

Or, you can eyeball it. The MPGe numbers are based on EPA ratings. If you normally drive your car in a way that beats the EPA numbers, I’d take the EPA numbers for the EV, correct for the same ratio and calculate based on that as an annual average cost.

 

Sorry, if I caused any confusion.

The little e stands for equivalent. So while its official use is alomots exclusively for electrics, we could be using it for diesel, natural gas, E85, etc. It is used for hydrogen FCEVs, but the energy content of a kg of hydrogen is really close to that of a gallon of gasoline. Which means slipping up MPGe and mi/kg in polite conversation is no big deal.

The EPA rating is just the EV efficiency. Except for cases like the PiP, in which a PHEV can't complete the test cycle on EV alone, that MPGe value includes any fuel burned during the test. Other official ratings may include both. The window sticker of first year Volts had a combined EV and hybrid MPGe included.

MPGe came about in order to make it easier for the general public to compare the efficiency of EVs to ICE cars. No need to mess with it if your personal use is to just track your fuel efficiency and costs; just stick to a kWh rating. Now, it might be useful for figuring out the best use of EV and HV mode is for trips beyond the EV range. I don't know of any aps to make such tracking and calculations easier.

MPG and MPGe is mostly an US thing; other countries may use MPG, but they may also be using a different gallon. So a foraign model not displaying it isn't surprising.

I just want to point out that you can use your known ratio of actual to EPA MPG, get estimates for what you will return for other cars while shopping.

 

Thanks for this. I think I will stick with kWh for the cost part of my analyses. My understanding was that "MPGe is just another way of showing miles/kWh", but seems like people are saying they are not the same thing.

Is there something wrong with my understanding and calculation below?
133 MPGe is the EPA rated value for EV drive portion of PRIME, not including HV run
25 miles is the EPA rated range of EV drive portion of PRIME from a full charge.
1 gal of gas = 34.02 kWh energy equivalent
133MPGe is the same thing as 3.91miles/kWh (133/34.02=3.9094)
Meaning the 25 miles EPA reported EV range is using 6.39kWh of electricity (25/3.91=6.39) to achieve this.

My at wall measure of electricity using L1 EVSE has been 6.5~6.8kWh/full charge which is close to calculated numbers from EPA rating. Slight excess has to be the "loss" at wall amount. My EV ranges have been 18 miles in the coldest time of winter to 36 miles in the best run situation in warmer temp, but the average is very close to the EPA range of 25 miles, or probably a few miles better.

 

MPGe is just a conversion of miles/kWh for the majority of EVs available.
It can also be used as a comparison unit for the efficiency of any fuel, or blends of several over a trip.

The formula listed in the Wiki article is for the latter. It works for the first, but as you discovered, there are simpler ways of reaching the same result.

Your watt meter could be making your EVSE's connection a little less efficient than directly plugging into the outlet. Or more likely, it is because of the cars used for the EPA test. They do not have to be actual production models, and often not because of test timing and production schedules. These hand built cars can, and do, have their component connections, panel gaps, etc. optimized for the test.

 

In addition to what Trollbait said, I believe the EPA numbers are based on 220V level 2 charging. Level 1 charging is less efficient, which will add to the amount of electricity drawn from the wall. The Watt meter, as Trollbait said, may reduce that efficiency by a bit as well.

 

Yeah, kind of a weird "test" when the EPA lets the manufacturers run the test on their dynamometers in the enclosed temperature controlled building. How their tested vehicle rates on the test may not be the same as one you buy off the lot in the same test chamber. That is why Consumer Reports buys cars anonymously and runs their "real world" tests outside so their readers have an idea how a vehicle actually rates compared to how other vehicles actually rate.

Of course you can't take EPA or CR's numbers as what a specific individual will get. My sister gets about the CR 44 MPG average for her 2005 Prius. Our Gen IIs typically do that in the winter and about 10 MPG better in the summer. The difference? We live in NW Vermont with winter, snow tires, not all that much traffic or traffic controls on lots of roads. She lives in way overpopulated So. Cal where you can't even hope to slow to maintain some speed at signals. Give the other drivers a car length or so of space between you and the vehicle in front and it will get filled so they can get to the red light faster. Open enough space so you, barring any other cars on the road, can drop only maybe 10 MPH by the time you reach the vehicles at the light that are moving when it turns green and you'll feel like you are driving backwards just to keep from tailgating all the "merging" vehicles.

That seems to fit with my short time with my car. I tend to get 3.9 to 4.1 miles/kWh on my EV driving. Not sure how I improve on that since I drive any vehicle I'm in like it was a Prius. Managed to get (total driving, not just highway) 3 MPG better than the EPA highway in a rented Rogue (wife's car getting repaired after she was rear ended) over a 1 week period.

 

When the purpose is to allow a comparison between models and brands, with a limited budget, I can't think of a better way to do it.
As you said though, these tests should not be taken as a statement of what any particular owner will get, just a benchmark.
Part of the fun I always had with my Gen 2 was to see how much I could beat the EPA numbers by

 

Yep! I had several 10+ gallon tanks at just over 60 MPG in my 2004. On the right roads in the right weather, it can be done.

 

Needs greater electric mileage. For the amount of driving I do (including steep hills). Its not enough but thankful enough that's it can cover the rang that its able to do.

Not to mention its not the prettiest hybrid out there.

BMW and Benz were competent enough to make their plugin look like .... normal car. imagine that.

plus stigma about prius drivers


Posted via the PriusChat mobile app.

 

there aren't enough ev's on the market (outside cali) to make mpge worth bothering with. but hopefully it will be useful someday

 

That brings back my burning question about reported electricity draw at the wall by many L2 EVSE users. How Much Does it Cost to Charge? | PriusChat I have seen many stating it is 6.1-6.3 kWh. But with my L1 it is always 6.5-6.8kWh. In fact, the calculation from EPA rating for which Toyota might have done under an ideal condition in the laboratory is suggesting the full charge requires 6.3948kWh, which is higher than real-world report.

If you are getting 3.9-4.1 miles/kWh right now, it will only improve with warming up of the temperature. I have had as high as 7.1 miles/kWh in moderate temperature but during winter it gets as low as 2.1 miles/kWh in severe cold days. My average was 4.3 miles/kWh for the first 12 months.

 

I don't understand what your question is?
As stated before, L1 charging is less efficient than L2 charging. As such, it will take more power from the wall to fill the battery with a L1 charger that it does with a L2 charger. This is supported by the numbers you have seen.

 

L2 charging reported in various threads in PC concluded that full charge for PRIME is 6.1- 6.3 kWh. This number is less than Toyota's own number 6.394 kWh used for full 25 miles range calculated from EPA rating number. My L1 charge number is in agreement with this, but people who have reported 6.1- 6.3 kWh seems to have a more efficient charger than Toyota's L2. I'm wondering why this discrepancy.

 

Could be the charger, more likely it is a built-in buffer, or simply a matter of all batteries are not identical.
Your numbers are higher/less efficient than Toyota’s. Most other reports are within 2% - 5%, which isn’t a very big difference.

 

I like that explanation. After all, they provide less efficient L1 EVSE with the vehicle. It would be reasonable to think they took that into consideration for reporting the results.

 

Toyota and others aren't required to post what they got. The law only prohibits claiming results higher than the test; they can claim lower.

Plus the rounding of posted results by anyone can't be discounted.

 

The capacity, in kwh, of the battery is greater than the kwh required to recharge since they don't allow you to go from 0% to 100% SOC.
The capacity of the battery shrinks during colder weather.
The capacity of the battery gets bigger again during warmer weather.
The capacity of the battery degrades over time due to usage

Mike

 

Now, I hear this all the time and I know that's all true in the real world as you drive any battery operated vehicle.

But what does it mean by "capacity"? I see a drastic range reduction in winter cold month. Most of them can be attributed to the use of the heater. However, even without using a cabin heater EV range is shorter in winter, yet I am not seeing any difference in actual electricity that takes to fill the traction battery. It has been always 6.5-6.8kWh at the wall for me last 21 months. It takes the same amount of electricity to charge the battery fully in winter or summer?