*A fuel consumption comparison among same make and model cars are not straight-forward because it involves the variations due drivers (lead foot or feather foot), load, road type, weather, etc. Then it is even more difficult to compare different cars and, worse yet, ele., steam, and other types of cars. The mentioned 140 000 km driver must have been a feather foot person. * *To illustrate, SAE compiled and extensive survey to compare diesel and gasoline vehicles. Only. I am attaching it. It shows the dependence of the vehicle mass on fuel consumption. The scatter of data (not shown) was enormous - gas data dots in the diesel area and vice v. The above suggest some of the reason for that scatter. * *The SAE lines were the average of volumetric consumption. I added the green line to show the comparison as energy consumption (to compensate for the higher energy content of the diesel). * *I believe the SAE study points out the disadvantage el. cars will always have. While liquid fuel cars carry the equivalent of a child (tank 1/2 full) on the average, battery cars carry much higher mass, charged or "dead." This is one of the fixed disadvantages when it comes to energy consumption according to the graph.* *Note:* *I understand it was not clear in my table where it said ..... *both vehicles rate about the same in both cost-per-distance and energy-per-distance ... * Here are the numbers: The cost-per-distance was 0.047 $/km (diesel) vs. 0.046 $/km (ele.) Energy-per-dist. was 3.5 MJ/km vs. 3.9 MJ/km. * *PS:* *Nobody sent me the electricity consumption of a 100 000 km el. car. Maybe I want too much. How about 50 000 km. Or 10 000 km? None of us drives an el. car? Know nobody who does?* *Stan Jakuba *
On Mon, Jan 28, 2013 at 1:17 PM, John M. Steele <[email protected]>wrote: > Sorry, all the units got me confused. I meant to say MJ/km or per 100 km, > or even per megameter, energy/distance in any case. > > ----- Forwarded Message ---- > *From:* John M. Steele <[email protected]> > *To:* [email protected]; U.S. Metric Association <[email protected]> > *Cc:* U.S. Metric Association <[email protected]> > *Sent:* Mon, January 28, 2013 12:08:35 PM > *Subject:* Re: [USMA:52272] Re: Fuel economy in the real world getting > farther away from EPA estimates | cleveland.com > > Interesting. I'm not sure who your audience is or whether you are > looking for feedback. However, here are some thoughts. > > *Is the Passat an older car? Your reported fuel economy is MUCH better > than the current Monroney sticker for a 2013 diesel Passat > (city/combined/highway) 31/35/43. In the past few years, a lot of > emissions technology has been added to diesels to meet the current US > standard. I don't know if that explains the difference. > > *I agree with your tank-to-wheels and socket-to-wheels terminology and > that it reflects the way the vehicle's "fuel" economy is measured. > However, both petroleum products and electricity are metered at point of > sale. The term "meter-to-wheels" might be applied to either. Just a > thought, as it certainly isn't standard terminology yet. > > *I find presenting the data in every unit possible very confusing and hard > to read. My recommendation is to start with Monroney sticker info and > price per unit as used in the US, transform to proper SI, and do the > comparison in km/MJ. If your audience includes the metric-impaired, do an > auxilliary table underneath in US units, but avoid the flipping back and > forth on units. > > *From the Monroney sticker, I would include the Leaf's (99) MPGe rating as > well as the 34 kWh/100 miles and then expand on the story of mine-to-wheels > vs meter-to-wheels. Superficially, the Leaf sounds twice as good as the > Passat but is worse on a total life cycle basis (just looking at fuel, not > even thinking about manufacture of car and battery). I think that is the > key point, but perhaps it needs emphasis. > > *As diesel has a higher heat content than gasoline, there may be a slight > problem comparing diesel miles per gallon vs "gasoline equivalent" miles > per gallon. A gallon of diesel is about 1.137 gasoline equivalent gallons > based on Lower Heating Value. Of course, once you reduce all data to > km/MJ, problem solved. > > ------------------------------ > *From:* Stanislav Jakuba <[email protected]> > *To:* U.S. Metric Association <[email protected]> > *Cc:* U.S. Metric Association <[email protected]> > *Sent:* Mon, January 28, 2013 10:27:34 AM > *Subject:* [USMA:52272] Re: Fuel economy in the real world getting > farther away from EPA estimates | cleveland.com > > Attached is a detail comparison between a diesel and electric car. It may > not be easy to read, but so it is not easy to make the comparison. Try. > Stan Jakuba > > On Sun, Jan 27, 2013 at 10:00 AM, Kilopascal <[email protected]> wrote: > >> ** >> >> >> http://www.cleveland.com/business/index.ssf/2013/01/fuel_economy_in_the_real_world.html >> >> It seems that the fuel consumption ratings for the Ford Fusion aren't >> working out to what the EPA has published. Could this have anything to do >> with the fallacy of using mpg to measure consumption from a battery and not >> actual fuel usage? >> >> Those who might know more about the subject may wish to post a comment at >> the bottom of the article. Here is our chance to expose the fallacy of mpg >> when used in areas it doesn't belong in and offer a proper metric unit to >> give correct results. >> >> I might post later, if I'm convinced it is the use of mpg to measure >> something mpg is not intended and then mention the proper unit to use when >> I find out what it is. >> >> >> >> > >
z.xls
Description: MS-Excel spreadsheet
