Consumer Reports: 2010 Toyota Prius still most fuel efficient car in America

[cwerdna]

Consumer Reports: 2010 Toyota Prius still most fuel efficient car in America — Autoblog Green

Here's where they mention (on their tests) 32 city/55 highway and 44 mpg overall (w/o having a subscription).

[bwilson4web]

I read the online version from the Consumer Reports web site and found two interesting quotes:

The Driving Experience

Final report coming soon.

Also, I noticed:

• "Accident alert system - Not available" -- in this I somewhat agree because it is an option ONLY in the top of the line. It really needs to be an option for all models.
• "Daytime running lights - Not available" -- IMHO, I think this is a useful option and should be considered for future Prius.
• "Tire pressure monitor - Available" -- this isn't standard??

Bob Wilson

[UsedToLoveCars]

Not quite right.

Tesla claims the Roadster is 2x as efficient as the Prius.

[Politburo]

Tire pressure monitoring systems are required by federal regulation.

[Shawn Clark]

Originally Posted by UsedToLoveCars

Not quite right.

Tesla claims the Roadster is 2x as efficient as the Prius.

Not really. The Tesla is less carbon fuel efficient than the Prius based on its EPA test results: 28 kWh/100 miles.

At any rate, the Tesla doesn't run on "fuel" and therefore your claim is inaccurate.

[Shawn Clark]

Originally Posted by bwilson4web

• "Daytime running lights - Not available" -- IMHO, I think this is a useful option and should be considered for future Prius.

As a separate option yes, not bundled. I got saddled with them in my Tundra as part of a package, but DRL's are unsuitable for my use. I had to pay to have them permanently disabled. I would have been happy to have a fuse/switch so that I could re-enable them at other times, but that was not an option.


If DRL's are all or nothing, nothing is preferable.

[drees]

Originally Posted by Shawn Clark

Not really. The Tesla is less carbon fuel efficient than the Prius based on its EPA test results: 28 kWh/100 miles.

How do you figure that?

Originally Posted by Shawn Clark

At any rate, the Tesla doesn't run on "fuel" and therefore your claim is inaccurate.

Then where did all the carbon come from?

[Shawn Clark]

Originally Posted by drees

How do you figure that?

I worked through the numbers recently comparing the Volt with the Prius. You should remember it since you posted a thanks to someone posting clearly erroneous information as a rebuttal in that thread. I used a lower kwh/mile value of 0.250 kwh/mile for the electric and it still lost. Use 0.28 kwh/mile for the Tesla from its EPA testing and it will fare even worse. You can even apply the DOE's 0.83 factor for well-to-tank gasoline to the Prius, and about 0.98-0.99 for coal mining, and 0.92-0.93 factor for average U.S. electrical transmission losses if you like. (I'm assuming the 0.28 kwh/mile figure includes Tesla's reported charging losses, 0.86 efficiency, so don't double count that.)

The Prius still comes out about 17% ahead by my estimate...and I get about 10% better mileage than the EPA combined figure so it is even higher for me.

Note that I'm not even considering the differential energy cost for the battery production. Full hybrids get more "bang for the buck" from their batteries than any EV does with present battery technology. Hybrids use maybe 1/10th as much battery capacity. Production cost of the additional battery pack is a crude measure of this. Add on tens of thousands of dollars worth of battery and try to convert that into energy consumption over a given vehicle life. (150,000 miles, 200,000, 300,000...it can't be very pretty even with high values.)

All in, it is likely no contest.

Then where did all the carbon come from?

Well, nobody stuck coal or water in the tank, and electricity is not "fuel." It was a silly statement by the previous poster considering that the article was clearly not referring to electrics. Might as well throw in bicycles or Amish buggies to really muddy the comparison.

You can't do apples-to-apples with electric, only approximate, because its energy/carbon efficiency varies greatly depending on the source of electricity. For my situation where ~100% of my electric comes from an aged coal plant within about two linear miles of my home I have no doubt about the basis. Electric loses easily to a hybrid like the Prius. That was a bit of an epiphany to me when I finally ran through the numbers. My interest in EV has evaporated since it is a false economy for me.

By the way, why didn't you ask the other poster to explain himself instead of me? Afterall, the one making the original challenge is the one that needs to back it up with some proof. A carmaker's hype is about as far from proof as one can get...especially when you look at Tesla's numbers and notice the cherrypicking.

It's not that I wan't EVs to fail or don't see them as a necessary progression. It is that electricity production is so inefficient from a carbon standpoint at present. We still have a long ways to go.

[drees]

OK, since Shawn didn't post his full numbers, I found these from this web site which appear to be OK on the surface (I did not research the numbers to validate them):

I was (partially) wrong Climate Sanity

Basically claims that:

50mpg = 0.39 lbs CO2/mile
EV[1] = 0.37 lbs CO2/mile
EV[2] = 0.58 lbs CO2/mile

Where EV[1] is the national average for electricity generation (1.34 lbs CO2 / kWh) and EV[2] is coal heavy electricity generation (2.1 lbs CO2 / kWh).

So what does this tell us? On the whole, going EV is good! We slightly reduce our carbon footprint, significantly improve local air quality where it matters most, and also reduce our trade deficit.

Sure - if you live in an area where your electricity comes from dirty, old, inefficient coal plants, then yes - you probably should pay a bit extra for renewable power. And even then - there's the previously mentioned benefits, not to mention the fact that the grid is moving away from coal power with it being replaced primarily by renewables and very efficient natural gas.

Edit: I found this cool website which lets you look up how dirty/clean your electricity is compared to average. The data used is a bit newer than the article above (1999) using data from 2005. I looked up my zip code and my electricity emits 0.724 lbs CO2 / kWh - nearly half the national average. In other words, an EV would be like driving a 100 mpg car in terms of CO2 emissions - not to mention all the other benefits of driving an EV (like the fact that I should have solar panels on my roof by the end of the year, thereby reducing the emissions of my electricity even more!)