Ethanol Added and Premium Fuels Are a Questionable Bargain
Over the last year, I’ve been keeping careful track of the fuel efficiency of my 2004 Honda Pilot. You know the vehicle – it’s the one I bought off of Craigslist a few years back.
My driving in the vehicle is an almost equal mix of highway driving, interstate driving, and stop-and-go driving in town. The terrain in central Iowa is mostly flat, but there are a few hills here and there. Over the last year, which amounts to the last twenty two fill-ups using a variety of fuels, the vehicle has averaged 19.1 miles per gallon.
Given that information, I wanted to assess the efficiency of different kinds of fuels that are available for sale here in Iowa and figure out which one actually gave me the best fuel efficiency for the dollar.
I really wanted to figure this out for myself because one of my closest friends swears that the ethanol blends are a rip-off. He avoids them like the plague and keeps meticulous track of his fuel efficiency in his car.
His theory is that the ethanol burns away and does virtually nothing for your car, so unless it’s 10% cheaper than the other choices, it’s not a good deal.
I wanted to put his theory to the test. Was the ethanol completely useless in my vehicle? Or was it just really inefficient? Let’s find out.
My Fuel Options
In Iowa, most stations offer three different choices for gasoline.
10% Ethanol to 90% Gasoline Blend
The “cheap” gas option. It’s listed as having an 87 octane, but it’s generally known to not be quite as efficient as the other options. I’m really curious as to how much less efficient it is. At my nearest gas station, it’s currently for sale at $3.46 per gallon.
This option isn’t blended with ethanol. It’s also listed as having an 87 octane. At my nearest gas station, it’s currently sold at a price of $3.68 per gallon.
This is listed as having a 91 octane. Again, at my nearest gas station, it’s currently sold for $3.90 per gallon. In general, I don’t see any evidence that premium additives do much of anything. I’ve virtually never put premium fuels in my Honda Pilot and at my latest maintenance stop, the engine was in wonderful shape.
My Plan to Compare Fuels
I wanted to determine which of these fuels gave me the best “mileage for the buck.” The proportions between these gas prices are pretty standard. The ethanol blend is usually about 6% less expensive than the normal blend, and the premium blend is usually around 6% higher than the normal blend, which matches up really nicely with the current prices.
My procedure was simple. Over the last three fuelings, I ran that Pilot until the “low fuel” light appeared so that I could be sure that my tank was filled almost exclusively with that type of gas. I would mark the odometer reading, then fill up with a particular gas type and drive my vehicle with that fuel until the “low fuel” light appeared again. At that filling, I’d mark the new odometer reading as well as the number of gallons that I added to the tank.
By simply subtracting the old reading from the new one, I would know how many miles I got from that tank of gas. By dividing that number by the number of gallons that I burned, I’d know the fuel efficiency that was provided to me by that gas. Then, I could divide the price of a gallon of gas by that number to figure out the cost per gallon of fuel.
May the cheapest gas win.
How Did the Ethanol Fuel Compare?
Unsurprisingly, the inexpensive ethanol blend was the worst performer. My fuel efficiency using the 10% ethanol blend, averaged over two tanks, was 17.9 miles per gallon.
The unblended “regular” fuel did much better. Averaging out my fuel efficiency over the course of two tanks, the “regular” fuel clocked in at 19.2 miles per gallon.
The premium fuel was actually the best of the lot, but I’m not sure whether it was outside of any margin of error. Over two tanks, the premium fuel gave me 19.5 miles per gallon.
The ethanol blend was bad, but did the low price make up for it? Was the top performer worth the premium cost? Let’s do the math.
The Cost Per Mile
The cheap fuel cost $3.46 per gallon. If I divide that by 17.9 miles per gallon, the ethanol blended fuel costs me 19.3 cents per mile.
The unblended 87 octane fuel costs $3.68 per gallon. If I divide that by 19.2 miles per gallon, the unblended regular fuel costs me 19.2 cents per mile.
The premium fuel costs $3.90 per gallon. If I divide that by 19.5 miles per gallon, the premium fuel costs me exactly 20 cents per mile.
The unblended 87 octane fuel is the best bargain, but just barely. You’re not really getting “ripped off” if you buy the ethanol blended gas. By my measurements, it’s just slightly less efficient for the dollar than the normal gas.
So, yes, the ethanol portion of the gas is really inefficient. It’s not completely useless, but it’s inefficient enough that the unblended gas at the same octane rating becomes slightly cheaper per mile.
The “Fuel Saver” Factor
There’s another important factor to look at in this comparison: fuel saver programs. Many stores offer “fuel saver” plans where they offer a cent or two per gallon in discount if you buy a particular item at the grocery store. Many people – including myself – will wait until they have a number of discounts and use them all on a single fueling.
How does that affect things?
Let’s say I hit the pump and I want to use $0.20 per gallon as a discount on that purchase. This lowers the price of the cheap fuel to $3.26 per gallon, the unblended fuel to $3.48 per gallon, and the premium fuel to $3.70 per gallon.
Under these conditions, the cheap blended fuel comes out on top at a cost of 18.2 cents per gallon. The unblended fuel is still cheaper, but the fractions turn out to be a bit closer; it still rounds to 18.1 cents per gallon.
The cheap blended fuel only becomes cheaper when your fuel saver discount is at approximately $0.40 per gallon (or more). This varies, of course, depending on the price of gas at a given moment.
A Note About Margin of Error
This is far from a scientific study. This entire discussion is based on my own observations in one vehicle over only a handful of fill-ups. While it’s enough information for me to make a fuel choice, you should make up your own mind about what you should be putting in your vehicles.
The results did approximately match what I expected from the beginning, given my knowledge of ethanol blends. The ethanol portion is inefficient, but not worthless, when blended with normal gasoline and used in a typical car.
What This Has Taught Me About Fueling My Vehicle”
Here’s my strategy:
There’s no reason to do so in my owner’s manual and it’s the most expensive option, so I skip it.
I let my Fuel Saver card build up a lot of discounts.
I don’t use it with each fueling. Instead, I usually try to use it on the first of each month (or very close to it) so that I stack up all of the discounts at once.
On normal fill-ups without using the Fuel Saver card, I get the unblended gasoline.
Without any discounts attached, the unblended gas seems to be the most efficient in my vehicle.
On my monthly Fuel Saver fill-up, I use the ethanol blended gas only if I have a good discount built up.
I keep a note of my Fuel Saver discounts and when the total is over $0.40 a gallon or so, I use the cheap stuff. Otherwise, I still fuel up using the unblended stuff.
All of this doesn’t make a huge difference, but buying the cheap fuel is easy to do.
It turns out that the savings is only a fraction of a cent per mile, but it still adds up and this policy is completely effortless. It just decides which nozzle I pick up when I’m at the pump.
If you live in a state like Iowa where ethanol-blended fuel is sold, avoid it unless it’s more than 6% cheaper than the normal unblended gas. From what I’ve observed, the percentage difference in the prices stays pretty constant, but it does change from state to state.
May your fill-ups always be cheap!