I have my 05 pre-owned hybrid for almost 2 months now and I am currently on my 2nd Gas tank. Currently I have about 33k Miles(still under warranty). FYI I am not driving my car that much. I have put maybe 400-500 miles so far

The first gas tank gave me 35mpg Highway or 31mpg Mixed for the whole tank( I was very satisfied with that), however after I filled the second gas tank I saw my milage go to 27 Highway at best or 21mpg mixed. I observed this behavior almost right after I filled up the car for the second time.

This is a MAJOR change in mpg performance. The other thing I noticed is that the idle from a cold start has gotten a little unstable(very slight vibration) which goes away afte the engine warms up. Other than that the car performed fairly good and the IMA seem to be behaving the same way like before.

The crazy thing is that I put the same exact gas(regular) from the same exact gas station. I do not know if this has something to do with the Winter gas blend.

For the time being the only thing I did has to add a bottle of Techron fuel system cleaner.

Has anyone experienced anything similar relating with Gas type.

Any recommendations?

Thanks

Mike