Can anyone tell me more about this? What is it's purpose? Will one of the benefits be I won't have to worry about my tank rusting out?<br><br>I learned about it from a diagram on egroups:<br>www.egroups.com/files/toyota-prius/Pri-Tank.jpg

No, - it has nothing to do with rusting.<br>Bladder is there to fill an empty space to prevent gasoline vapors.<br>This way / according to TOYOTA / they eliminate vapors emmison by 90%.<br><br>Robert

Sure can - I posted the pic.<br>There are a few of advantages to a bladder tank:<br>1. Safety - no (or very few) fumes in the tank. The bag collapses as the fuel is used: a BIG "Playtex Nurser" baby bottle from which your Prius sips gasoline. No fumes - very little chance of turning into a "TWA Flight 800" in a collision. The bag in inside a steel tank.<br>2. Environment - No fumes - no leakage to the outside world - much less nasty hydrocarbons in the atmosphere.<br>3. Longevity - Nothing to corrode, rust or flake off inside the gas "tank" and muck up the fuel-injection.<br>What's to rust? <br>Bill Powell

William,<br>As I understand it from the engineers,the primary motivation in the use of the bladder tank was to capture the evaporative emissions. In a normal ICE with the engine operating all the times provides the vacuum to purge the charcoal canister....in prius' case the engine is off a good portion of the time so another means had to be developed...the bladder tank. Another interesting feature of this tank is that it contracts (the plastic liner)during extreme cold temperature - hence a lower capacity and range at 20F. PM

Priusman,<br><br>&gt; Another interesting feature of this tank is that it <br>&gt; contracts (the plastic liner) during extreme cold <br>&gt; temperature - hence a lower capacity and range <br>&gt; at 20F.<br><br><br>+20F is WARM in Minnesota during the winter! <br><br><br>How much capacity will be lost?<br><br>What happens when the temp drops from +15F to -5F overnight? <br><br><br>The fluctuation of cold temperatures is a common occurrence in the upper-midwest every January. In fact, during the course of the entire winter it will range from +35F to -20F. What will that do to the integrity of the plastic liner? (I don't expect there to actually be any problems since, as I understand it, testing was done in the cold weather testing facility in Ontario.)<br><br>JOHN<br><a href=http://home.att.net/~john1701a/ target=new>http://home.att.net/~john1701a/</a>

John,<br>cold weather testing in both norther minnesota and northern ontario. According to the engineers the contraction in the liner is from ambient to 15-20F...and there should be no further contraction below that point. I used to know reduced volume amount but I'll need to confirm before I post it. I don't foresee any durability issues.....as part of the emissions control system....the vapor recovery system must stay in compliance for quite some time....PM