As a soon to be new Volt owner, I question the need for Premium fuel.
Exactly what is the octane needed?
The seems to be 3 choices of fuel, unleaded, plus and Premium.

This seems to be a real "bummer" to buy a fuel efficient auto and then have to pay $.30 more a gallon.

Please help me understand this.

Chuck
Chico, CA

http://gm-volt.com/2010/07/30/why-the-volt-requires-premium-gasoline/

Earlier this week GM released the 2011 Chevrolet Volt ordering guide for dealers to use. Included in the description about the gasoline generator were the words “requires premium fuel.” This led to specualtion and surprise from fans and skeptics as to why in the world the car would require premium gas.

According to Volt vehicle line director Tony Posawatz, there are two main reasons.

“The Volt is all about efficiency,” he said. “Premium fuel offers the opportunity to have a little bit more spark.”

“Ninety one octane fuel also offers the opportunity to be a little more efficient, he added. “So technically its a five to ten percent fuel economy improvement the few times that most people will run the range extender.”

Posawatz also claimed the increase is cost will be offset by the efficiency gains.

“Based on our calculations the fuel economy and efficiency gains you get will effectively compensate for the extra cost of premium fuel,” he said

Additionally, premium fuel is apparently slower to go stale.

If people are not using the extended range capability a lot, the premium fuel does last a little longer,” he said

“There will be a few that will have their gas go bad,” he added. “We have ways to address that as well.”
The AAA Fuel Gauge Reportshows the current national average price for a gallon of regular unleaded gasoline is $2.74. The national average for a gallon of premium gasoline is $3.01.

I would say the easiest way for owners to address the stale fuel issue is to pour a bottle of fuel stabilizer in the tank if they're deliberately trying to run the ICE as little as possible. One of my early suggestions (I can't remember if I posted it here or on another forum) was for GM to have an on-board fuel stabilizer tank that would mete out stabilizer into the fuel tank on an as-needed basis (based on use and frequency patterns) to keep the fuel fresh. Seems like an auto-run function is built-in, but my understanding is that it can be over-ridden by the driver, and I'm sure there will be some fanatics that will keep hitting "No, No, No." My question would be if GM will continue to honor the warranty, or will deny warranty claims on grounds of "deliberate neglect and negligence against recommended service intervals."

I would say the easiest way for owners to address the stale fuel issue is to pour a bottle of fuel stabilizer in the tank if they're deliberately trying to run the ICE as little as possible. One of my early suggestions (I can't remember if I posted it here or on another forum) was for GM to have an on-board fuel stabilizer tank that would mete out stabilizer into the fuel tank on an as-needed basis (based on use and frequency patterns) to keep the fuel fresh. Seems like an auto-run function is built-in, but my understanding is that it can be over-ridden by the driver, and I'm sure there will be some fanatics that will keep hitting "No, No, No." My question would be if GM will continue to honor the warranty, or will deny warranty claims on grounds of "deliberate neglect and negligence against recommended service intervals."

I'm one of the guys saying NO! The volt monitors engine use and fuel consumption. Other posts have detailed the maintenance intervals including gas refreshment and oil changes. However, the Top Tier fuel GM recommends has 8 - 10 % alcohol in it to absorb condensation from the fuel tank. GM does recommend a GM brand fuel additive, but I'd stay away from that as well. I'd be happy taking a trip in the Volt once in a while, driving in CS Mode just to keep all the systems working. Apparently Onstar is watching and will notify me of anything amiss.
The only override I've found is the Oil Life Interval. You have to manually reset the function once the oil is changed.

VIN #63 is in the driveway, safely charging!

Seems like an auto-run function is built-in, but my understanding is that it can be over-ridden by the driver, and I'm sure there will be some fanatics that will keep hitting "No, No, No." My question would be if GM will continue to honor the warranty, or will deny warranty claims on grounds of "deliberate neglect and negligence against recommended service intervals."

If you say no to the Engine Maintenance Mode request too many times the Volt will do the EMM without asking permission. In addition, the Volt will perform Fuel Maintenance Mode by running the engine to use up any fuel which has been in the tank for a full year.