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I just finished my first real cross country trip in the Prius and noticed some really weird behavior with the fuel tank. Nothing bad, mind you, but it can throw you for a loop. Here's what happened:

Start of trip I decided to top off the tank as I had driven back and forth to work a few days and wanted to start from scratch with a completely full tank. So I did.

Got to first fuel stop some 330 miles away and put in 8.5 gallons. That indicates a 39 MPG trip on the interstate with AC.

Second stop was after 181 miles. Put in 2.5 gallons. That is 72 MPG, same interstate, AC on. I did the second stop to fuel up with E-10 before I passed out of the E-10 market, and since it was only 50 more miles to my destination, that was okay.

So, I drove around a few days then headed back. Stopped to fill the tank and put in 6.9 gallons after 289 miles. Now we are back down to 41 mpg.

Went 297.4 miles and filled again - 5.8 gallons and 51 mpg.

Got home and filled up the next morning on the way to work. 215 miles and 3.2 gallons for 67 mpg.

The numbers are completely bogus. They have to be. 72 and 67 mpg on the interstate with AC? No way.

So, time to recalculate it: 1321 miles, 27 gallons and 48.8 MPG. Guess I should have gone longer between fillups, but wanted to make sure I was running on E-10 fuel.
 

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> Guess I should have gone longer between fillups

That's it exactly.

You can't allow the pump to stop itself at the correct time when only topping off, because it won't. It will almost always overfill, which is never a good thing since the excess goes into the charcoal canister.

So if you need to top off, do it yourself. Use the Multi-Display MPG value as an indicator of how much gas you should add.


> wanted to make sure I was running on E-10 fuel

I've never heard anyone make that comment before. I have heard exactly the opposite though. When talk of replacing MTBE out on the West Coast began, some people feared the damaged E-10 could supposedly do... not realizing that those in the Midwest have been using it without any problems for over 10 years already. (We even have it available in low-sulfur too!)
 

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Discussion Starter #3
john1701a said:
> wanted to make sure I was running on E-10 fuel

I've never heard anyone make that comment before. I have heard exactly the opposite though. When talk of replacing MTBE out on the West Coast began, some people feared the damaged E-10 could supposedly do... not realizing that those in the Midwest have been using it without any problems for over 10 years already. (We even have it available in low-sulfur too!)
That's all I use in the Prius, John. Unfortunately, here in my area anyway, only Casey's General Store seems to sell the stuff. So, that's where I go. I have been trying for months now to find a list of stations that sell E-10, but the best I can do is the DOE E-85/B100 list. Anyone know of a list?

Speaking of which, I just recently wrote a bit about E-10 in this entry in my blog. There is some great info out there - even more info that what I really wanted to know.

Also, when Phillips 66 has their 87 octane selling for $1.709 a gallon here like they did last week, Caseys is selling 89 octane E-10 for $1.559. Go figure.

Oh, and the damage thing: That is the oil companies spreading FUD. Check out the Univ. of Washington paper. In states that require E-10 be sold, Exxon Mobil does everything they can to tell customers that E-10 is safe. Then in states that don't require E-10, they state the stuff is bad.
 

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Charcoal Canister?

What? I didn't think the Prius had a charcoal canister, that's why the funny plastic fuel bladder gizmo is there...

Did I miss something?
 

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Re: Charcoal Canister?

stevewa said:
What? I didn't think the Prius had a charcoal canister, that's why the funny plastic fuel bladder gizmo is there...

Did I miss something?
You missed the following statement in the New Car Features book:
"The ORVR (On-Board Refueling Vapor Recovery) is a system that uses a charcoal canister, which is provided onboard, to recover the fuel vapor that is generated during refueling. This reduces the discharge of fuel vapor into the atmosphere."

This is pretty much standard equipment on cars sold in the US. But it's not as effective in the Prius because engine vacuum isn't available when the engine shuts down. So they also incorporated a bladder in the fuel tank.
 
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