Hi vicious13: There is no benefit using a higher octane in your car if it is still factory tuned. Regular gas not exceeding E10 will be fine.
The main concern with gasoline containing over 10% ethanol is deterioration of the fuel system components. And it does produce lower fuel economy. Your 05 V6 will run fine on E10 but not higher concentrations of ethanol.
I mentioned fuel economy. Using a fuel with lower "E" content will result in slightly better fuel economy. However, the cost of using a premium fuel with E5 or regular with no ethanol (if you can find it) costs more than the additional cost to use a little extra gas containing E10. And I'm sure global gas prices have increased slightly this month.
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