pgmon

What's the Fuel Economy of Your Vehicle?

Sunday, 25. January 2009, 18:50:23

This morning I got up at 9 a.m. and turned the TV on to one of our local public broadcast television stations. On was Motorweek, a weekly show that talks about trends, tips, reviews, of vehicles. In this episode they discussed a nifty website where one can estimate the fuel economy of their vehicle. The government uses new standards for estimating fuel economy, and can show the results of the new ratings versus old. Here I decided to check on my 1986 Toyota Pickup, 2WD, 2.4L 4-speed manual. Occasionally on the highways, especially on long drives, I check the miles per gallon and I seemed to have consistently received around 28 to 30 miles to the gallon (or 12 to 13 kilometers per liter). As you can see, using its assumptions (15000 miles per year, 55% city, 45% highway) the fuel economy on my vehicle is actually not bad (again, based on the assumptions it produces about 7.1 tons per year of carbon dioxide emissions).

What's even niftier about the website is you can plug in your assumptions. Well, I ended using my present assumptions of 7500 miles (12000 km) driven per year, 65% city, 35% highway, and it calculated my overall average mileage per gallon to be about 25, with 3.4 tons per year of carbon dioxide emissions. Pretty cool, considering where I live is conveniently located by numerous bus stops (which I use as I'm still a student obtaining yet another master degree and my bus pass subsidizes costs) and many shopping opportunities within a one-mile radius (1.6 km). This will all probably change as soon as I actually get back into the real world, but I'll still try to continue using present habits, such as using public transportation, walking, and even biking, where I can. Check the website out! It also discusses alternative fuel vehicles

Library Use IncreasesWhat Are The Odds?????

Comments

Colin # 27. January 2009, 02:44

It took me a bit to find the specific webpage you were talking about. You have to click on "Find Your Car's Energy Impact Score" and lower down on the page you can "personalize" the mileage figures for your driving. They don't cover diesel vehicles for these estimates, I wonder why?

Hey, do you know how they estimate tons of carbon dioxide? I'm curious because your 7500 miles per year (that's surprising low by the way, nice job!) converts to only 300gal/yr if you average 25mpg. 300 gal at about 6lb per galon = 1800lb which = (approx) 0.09tons of liquid petroleum (I'm using 20000lb/ton). How is that calculated into 3.4 tons of CO2, according to what the website calculated for you?

pgmon # 27. January 2009, 17:24

Yah, I totally saw that they don't really compare diesel. Kind of weird, actually. Regarding the calculations, I compared it to other websites which calculate CO2 emissions and they were within range of what I got. At one website, http://www.earthlab.com/carbon-calculator.html, they give you an idea of how the calculations for CO2 emissions can be derived.

Quote, "To estimate auto emissions, the calculator divides the average number of miles an American drives in a year (12,000 Miles) [US Environmental Protection Agency, Office of Transportation and Air Quality, "Emission Facts: Greenhouse Gas Emissions for Typical Passenger Vehicle," February 2005] by the estimated fuel efficiency (21 mpg) of the average American vehicle. This amount is multiplied by 19.564 [U.S. Department of Energy and the Energy Information Administration, Instructions for Form EIA 1605B, Voluntary Reporting of Greenhouse Gas Emissions] the amount of pounds of carbon dioxide that is emitted as a result of burning one gallon of gasoline. To calculate metric tons, this number is divided by 2,205."

One can substitute their own actual average miles driven, and estimated fuel efficiency to calculate their estimated CO2 emissions from driving their vehicle.

Regarding diesel engine CO2 emissions, go to http://www.epa.gov/oms/climate/420f05001.htm#calculating. Quote, "CO2 emissions from a gallon of diesel = 2,778 grams x 0.99 x (44/12) = 10,084 grams = 10.1 kg/gallon = 22.2 pounds/gallon."

Oh yeah, you might be using wrong conversion numbers. There are only 2000 lbs per ton, not 20000.

Colin # 28. January 2009, 01:43

OK Thanks for that. I wasn't really doubting the calculations were done right using their standards (mine werent with the incorrect conversion to tons). However, it's still strange they figure 19.564lb of CO2 are emitted from one gallon of gasoline when liquid gasoline only weighs abouat 6lb per gallon. I just realized CO2 is two parts O to each part C, so when gasoline combusts and combines with O2, it must pick up mass at that point. That must be it... heavy suckers, those O2's.