@John: We have "declared Porsche to be the greenest car company around" ... excuse me?

@Chris: I'm a journalist, not an advocate. If you want advocacy, there are many fine sites produced my uncritical advocates.

I report the news, but I try hard not to do so uncritically or without context. Many, many outlets regurgitate press releases without adding any value. If you prefer that, there are many sites that take that approach.

At the risk of sounding sanctimonious, there are no easy, cost-free answers. We try to add context and a sense of the challenges around all of the possibilities that present themselves as "green."

We think of it as reality. Again, my 2 cents after doing this for a while.

@Chris: We've already seen 1 boom-and-bust cycle in domestic corn ethanol production. Biomass ethanol is progressing far more slowly than predicted. And Congress killed all ethanol subidies:
http://www.greencarreports.com/news/1071085_congress-actually-ends-taxpayer-funding-of-ethanol-subsidies

Now, at least one study says that we simply can't achieve legally mandated amounts of ethanol in our fuel:
http://www.greencarreports.com/news/1075895_ethanol-goals-passed-by-congress-cannot-be-met-new-study

Since E85 vehicles produced CAFE credits for NO net improvement (since the vast majority did not & will never use a single drop of E85), it seems sound policy.

My 2 cents after covering it.

@Stiofan: Both petrol and diesel are considerably less expensive here in the States than elsewhere in the world, so cost savings are lower. Diesels must meet much more stringent emissions regulations here in the States, so they cost more to certify for sale. And diesel is usually at parity or more expensive than gasoline, so calculating the savings gets complicated--unlike those European countries in which it is heavily tax-advantaged, so cheaper per litre at the pump.

@Kid Marc: Am I understanding you properly? You suggest that no one can be knowledgeable about hydrogen fuel-cell vehicles without a minimum of *30 years* of experience in the field?

If so...golly.

@Chris: Re/E85 compliance, I've heard that the cost to automakers is roughly $100 to convert an engine to accept the more corrosive E85 fuel.

All during the 2000s, they got extra CAFE credits for selling Flex-Fuel vehicles even if the buyers had no idea they could handle E85.

And of course the vast majority of those vehicles never used a drop of E85--but the $100 cost was the cheapest, easiest way for automakers to get their CAFE averages to where they needed to be. That provision of the CAFE laws is now going away, finally.

@Chris: The automakers' concern is that they will be blamed for any damage caused by E15 usage in vehicles that were never designed for it--and in fact were engineered long before E15 was even conceived of.

I need to check into whether 2010 and later vehicles are engineered to accommodate E15. But IMHO, it's a valid concern that if an otherwise serviceable, low-mileage 2006 vehicle incurs some kind of damage from E15 use, its owner will blame the automaker for something it didn't design for.

That said, running for 100,000 miles exclusively on E15 would be virtually impossible today and for at least a few years to come, since the fuel hardly exists today.

@Xiaolong: I disagree that "if you drive normally...you won't even get a single mile" [of electric range] in the Plug-In Prius.

As you note, it depends on driving style. If you floor it every time away from a stoplight, the engine will kick on.

If you accelerate gradually, however, the electric motor is capable of moving the car away from rest and propelling it for a handful of miles at speeds within the 0-to-45-mph range. It won't cover *every* driving situation by a long shot, but it will cover *many* usages in regular traffic. If steady gentle acceleration is driving like a grandma, perhaps more people should do it.

Have you actually spent any time driving a Prius plug-in?

@EV Enthusiast: Warning from your friendly site moderator: Please leave political name-calling OUT of our comments section. Please stick to discussing the facts of the article. OK?

@John: Hydrogen technology is improving "week by week"? RLY?