Gasoline vs Gasohol Real World Comparison
One of the myriad ways I manifest my geekness is that I track my gas mileage. After moving to rural North Carolina I began to notice that the mileage on my 10 year old Honda had improved by roughly 4 mpg to 27 mpg. At first I thought it was the fact that I don’t do much interstate driving anymore. Most of my driving is now on double lane rural roads with 55 mph speed limits, and it’s tough to go much faster with a pickup truck or grandmother in front of you. 80 mph on multilane interstates is a thing of the past.
The answer came a couple of weeks ago at the gas pump. Most of the gas stations do not offer gasohol whereas in the Philadelphia area E10 - or 10% ethanol – is the norm. I’m a big supporter of ethanol, especially the cellulosic kind, but being also a math geek I thought I would take the opportunity to figure out how much using E10 had cost me over the past 5 years.
I drive roughly 20,000 miles a year. Let’s assume that the average price per gallon of gasoline during the past 5 years was $2.75/gallon.
So had I driven 100,000 miles on pure gasoline at 27 mpg I would have needed a smidge over 3,700 gallons and spent $10,186 on gasoline during that 5 year period. On E10 at 23 mpg I actually used 4,350 gallons of fuel and spent $11,963.
| MPG | Gallons | Cost |
| 27 | 3,704 | $10,186 |
| 23 | 4350 | $11,963 |
| 646 | $1,777 |
So over a five year period I paid almost $1800 more in fuel using E10 than I would have using pure gasoline. That’s about $1/day more in fuel costs.
E10 is mandated in the Philadelphia area by clean air laws. Is it worth it? Since I make more than the average I can afford the additional cost, so it’s worth it to me. However for many others who drive 20,000 miles the additional $350+ dollars a year is an unnecessary burden.
Nick:
The E10 requirement means it takes you 4350 gallons of fuel to go 100,000 miles, and if you subtract the quantity of ethanol (10%) you still are burning 3915 gallons of fossil fuel. So instead of just burning the 3700 gallons required by standard gasoline you would rather burn an extra 215 gallons of fossil fuel, 435 gallons of ethanol plus the $1800 dollars to use E10? What am I missing?
24 November 2009, 12:45 pmScott Kirwin:
Nick
Good point. You would think that burning 10% ethanol would decrease mileage by 10% – but according to my mileage figures it causes worse mileage by an extra 5%. Hmm… I can’t explain that beyond blaming my methodology. I don’t have the data recorded in databooks. I just calculate the MPG on my Blackberry while I’m filling up. Maybe the extra 5% is due to slower driving. I can’t drive as fast on these 2 lane rural roads as I could on I-95.
I suspect that part of the problem is that my 1999 Honda’s engine is not tuned for ethanol. As it stands right now it appears that not only does ethanol fail as a “filler” but it actually worsens the gas mileage for the gasoline it’s mixed with. Ethanol does have energy in it, albeit not as much as pure gasoline. It should be adding something to the figures.
Now you’re making me wish I had taken better data while I lived in Delaware… Dang.
My point – poorly made – was that E10 was mandated by the government for environmental reasons, yet the cost to the consumer was hidden. Could that $1,777 have been better spent on planting trees, hiring environmental inspectors to enforce laws, or other ideas that could have had a greater positive impact on the environment? I would hope so.
24 November 2009, 2:05 pm