New 2014 Prius MPG Problem- Help me figure out what Im doing wrong!

Although I've never seen it published, I'm sure there could be a difference in energy density between different fuels. I've noticed differences in fuel economy between different sellers over the years. Driving the same trips, filling the tank to the same level, calculating fuel economy every time, is what convinced me there is a difference. While it's hard to tell exactly whether you are getting summer-grade or winter-grade, or some blend of the two, the difference in fuel economy between summer and winter driving is unmistakable. Separating out the fuel-grade factor from this is impossible.

Mandates vary, but winter grades generally have a higher Reid Vapor Pressure (RVP) therefore it seems to suggest that winter fuels are more volatile, therefore might contribute to better fuel economy. Of course, it's impossible to say this with certainty, so I remain hopeful that some hard research comes my way on this topic.

 

Welcome to the forum.
And a big THANK YOU for reading before posting.

 

Of course

 

Here's an article that should answer all your questions; it's actually the summer blend that contains more energy (1.7% more, according to the US EPA).

 

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if you are driving at 70 to 75 mph ... 44 mpg during the winter time is about right - you could get better fuel efficiency if you drop your speed closer to 60 mph. The Prius also gets slightly less fuel efficiency in the wintertime because - winter blend gas has less energy per gallon. If your commute is under 5 minutes, the Prius cold start MPG handicap is even worst when the outside temperature drops below 50 degrees Fahrenheit. The only way I know to avoid this cold start penalty is to pre heating the ICE coolant with an Engine Block Heater. Grill blocking isn't going to help fuel efficiency in the winter time by much if your commute is only 5 minutes. With such a short commute, I am surprise you didn't get a plug-in prius or an electric car like the Leaf.

 

Exactly, also drive like you have eggs under your feet and make sure you get Mobile one 0W20 the next oil change.

I get the same the year around but always average a full tank over about 300-400 miles.

30-45MPH is my best MPG. 65-70 maybe 52-54 MPG with a full load Closer to 50 at 70MPH. 45-55 MPH is a sweet spot also.

 

Whoa whoa whoa, it has to Mobil?