There is no credible person or agency that says use low octane fuel for hybrid vehicles as a generic statement. It depends on the individual design.

So lets talk of individual vehicle manufacturer recommendations.

Toyota recommend use of regular 87 octane fuel in the Prius. The reason is it is a low compression engine. It doesn't need high octane fuel. So a litre of low octane fuel will be pretty much full of power delivering stuff you can burn, with little stuff that was added to boost the octane rating that may not burn.

Ditto for the Nissan Altima Hybrid, Ford Escape Hybrid, and Toyota Camry Hybrid.

I suspect it also applies to the Honda Civic Hybrid, but I don't know for sure.

Hybrid vehicles using the Toyota system have an engine tuned to the Atkinson cycle. Here the object is to have a long power stroke so you can extract as much energy from the burning fuel as possible. Unfortunately, if you have a long power stroke you also have a long compression stroke, and so would have to use high octane fuel and take other measures to avoid knock. In the Atkinson cycle, they hold the intake valves open for part of the compression stroke, to avoid high compression. The final result is a low compression long power stroke engine that only needs low octane fuel.

But as I said in the beginning, it is design specific. It could be different for a different design.

Pearl is a
2007 Driftwood Pearl Prius
Package "B" (everything but leather, nav, and rear camera)

Ditto to what he said!

I always buy the lowest octane possible.
In mountain states, ( over 3,500 feet? ) they sell 85 octane.
I get higher MPG from 85 octane than anything else.
I cringe when I visit other states and have to buy 87 octane.
I loose 3-4 MPG with this switch of just 2 octane.

Plus lower octane is cheaper!

Ahem, "kerpal" is a signature spammer. It posted five 'brain dead' messages but the signature was always the same to a commercial web site. To see what I mean, click on it's identifier and pull up it's only postings. SPAM, SPAM, SPAM, SPAM.

I sent a note to one of the moderators suggesting the "kerpal" have his signature modified to point to the GreenHybrid.com posting rules. The text would remain the same but clicking would just show the anti-SPAM rules of the road. Then lock out signature changes and wait for their reply. Of course 'teasing' a SPAMMER does no good, they are sociopaths.

When I realized it, I deleted my earlier reply about the Lexus 600h needing 93 octane gas. Then I found "kerpal" scrum in our longest running thread and the light came on. But two can play at this game:
There is a terribly worthless signature SPAM link being spread by "autopartswarehouse" that infects web browsers with a totally bogus display having nothing to do with hybrids or the real, autopartswarehouse.com internet service. The sociopath spreading this leaves unusually lame and inappropriate messages scattered in various threads. This pathetic link should be shunned and reported to the various Internet police authorities. There is evidence the sociopath may be violating their hosting terms and conditions.

Bob Wilson

ps. "Don't get mad, get even." USMC drill instructor

pps. I'll probably get a moderator warning . . . sometimes deserved.

Operation Iraqi Oil Freedom:

Automatic, stock, project car.

My other 1500 cc car:

Automatic, stock, backup car.
Free speech, dialog and knowledge thrives without the poison of SPAM.

The HAH is recommeded for 86 octane or higher.

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