According to Honda, the 2006 HCH has a plastic-resin fuel tank which helps with obtaining its AT-PZEV Emissions Rating "To achieve Advanced Technology Partial Zero-Emission Vehicle (AT-PZEV) status, a vehicle must be a Super-Ultra-Low-Emission Vehicle (SULEV) with zero-evaporative emissions and carry a 15-year/150,000-mile warranty on emissions equipment. Every 2006 Civic Hybrid has a new plastic-resin fuel tank that does not produce any evaporative emissions." Why doesn't Prius eliminate the bladder concept all together? Is it more a crash safety issue? Or more an emissions issue? or both ? As many posts and threads there are on the bladder issue, it really does seem problematic. Can't Toyota come up with a better solution?
I think it's purely an emissions issue. And I don't think it's as problematic as the posts would lead you to believe. I think the problem is that most Prius owners focus so much on the fuel consumption, that the bladder inconsistencies are over exagerrated. Is it such a huge deal that one time after driving 400 miles I can put in 8 gallons and the next time 10 and the time after that just 6? It's a bit odd, but considering you'll still get the same fuel economy, just fewer or more miles per tank, why should it be considered a problem. I did see in one post, how someone's tank would start blinking after 240+ miles or so. Now that I'd consider a problem (assuming they last filled up with more than 5 gallons).
The Hihys and RX400h have pressurized tanks or something along that sort. Owners have to wait a few seconds as the it depressurize itself then opens the fuel filler cap door when ready.
I think it's a cost issue. A bladder is probably the cheapest way to achieve an AT-PZEV rating. Note that the HiHy and the RX400 are not PZEV vehicles, they're SULEV. And they also don't have a bladder.
