I recently bought a 2010 Nissan Titan. Needless to say my gas cost (not including the recent price hike) went up due to the larger gas tank and worse fuel economy compared to the Toyota Tacoma that I was driving.
I discovered a couple of days after the purchase that it is actually a FlexFuel vehicle, meaning it can run straight E85 Ethanol or straight Unleaded Gasoline, or any amount of the two mixed together. So I checked in the owners manual and found that Nissan clearly states that when running E85, you will see a 30% increase in gas consumption because E85 has less “energy per gallon” than regular gasoline.
I found a station near my office that sells E85, and checked the prices. Unleaded was $3.59 while E85 was $3.39. Now that’s hardly worth the cost difference when you factor in the difference in MPG, however I decided to give it a try anyways. Nissan says if you are switching fuel types to make sure there is at least 1/4 of a tank of regular gas before you start running the Ethanol, and to run the vehicle immediately for at least 5 minutes after filling up, in order to prevent rough idle and engine knock — so they want you to wean the engine over to it.
I wasn’t sure how many gallons the tank would hold total but I was on empty — the dashboard display said 0 miles to go, so I went with the Tacoma’s half way point. I put 9 gallons of E85 in, then filled the rest of the tank up with Unleaded. It wound up being uneven anyways, the tank took 15 gallons of Unleaded, but oh well.
I’ve been driving for a couple of days on it and I haven’t noticed any decrease in MPG, probably because of the newness of the vehicle combined with the tank having more than 50% unleaded fuel. That actually made me think of something else I need to check into — “do the two fuels mix or are they like oil and water, where they separate and one sits on top of the other?”
Anyways, I decided to do some more research today, where I came across the article E85 and Fuel Economy. It was a pretty enlightening read, especially this quote: “The irony here is that although E85 in fact gets poorer fuel economy than gasoline, for CAFE purposes, the government counts only the 15-percent gasoline content of E85.” Here’s a little background in case you didn’t read the article linked above — CAFE stands for Corporate Average Fuel Economy, which is essentially a government mandated fuel economy standard that imposes stiff fines for auto manufacturers that don’t comply.
What all of that means is this: The government puts a mandate on auto makers to improve fuel economy. Their answer is a FlexFuel vehicle which uses E85 (85% Ethanol, 15% Unleaded), which has 30% worse fuel economy, but which 1) comes from plants so its supposedly better for the environment, and 2) is made in the US so it doesn’t ship money overseas. The manufacturers know they can’t get away with making vehicles with worse fuel economy, so somewhere in all of this, the government decided that they would only rate the fuel economy of the Unleaded gasoline part of the E85 (meaning only the 15% of your entire tank’s fuel economy is being rated for its MPG)
In simple terms, if you have a vehicle which holds 10 gallons of fuel, and which is running E85, 1.5 gallons of the fuel in your tank is Unleaded, and that 1.5 gallons is all that is being rated for fuel efficiency.
So if your vehicle goes 100 miles on a full 10 gallon tank of E85, they are saying you went 100 miles on 1.5 gallons of gas (66.6 MPG), rather than 100 miles on 10 gallons of gas (10 MPG)! Hardly what I would call accurate considering you paid over $3.00/gal for that E85.