First tank's mileage

First, I don't recommend worrying about mileage until the third tank, I needed time to familiarize myself with the car first.

How you 'fill' the car and what the dealer did are not usually similar.

It is winter, gas mileage may be 5 MPG lower than spring summer or fall. (Yesterday it was 70F here and I had summer mileage!)

If something were wrong, expect the dash to light up like a christmas tree

 

You've had the car 105 days, and you are still on your first tank of fuel? If this is a daily driver, then your trips are very short, making for severe driving conditions that cannot produce good MPG in any weather, let alone winter. Your low- to mid-30s MPG would be fantastic for such conditions. My Subaru would barely be in double digits, low teens at the absolute best in warmer weather.

If you don't drive this daily, what is your typical trip length?

 

This is exactly what I was thinking.

 

I have my new 2011 for two weeks. My "dealer fill" gave me 45 mpg (calculated using actual gals required, and it's been cold in PA. I wonder if your tank was filled even though 10 pips were on the guage.

 

:doh:

Can you confirm if this 105 day timeline is accurate or not???

 

Your first tank lasted less than two weeks, so you appear to be driving more than 25 miles per day

OP's first tank is lasting longer than 15 weeks. If a daily driver, it is averaging less than 2 miles per trip, so it is possible that is has never even been fully warmed up. This is a recipe for horrible mpg in any combustion engine vehicle, so the fact that this tank has produced 289 miles strongly hints that it is really was filled.

With this driving pattern on my non-hybrid, with a one-third larger tank, the needle would be on 'E' somewhere around 140 to 175 miles.

OP brought this car home October 5:

 

(I am always confused by why you would buy a Prius not to drive, that HAS to be hard on the batteries! All the Prius you hear going 250,000+ miles are never turned off.)

 

+1
You've got all that going aganst you ... plus even your brand new tire tread takes away high mpg's. When you're dealing with a car that can get 60mpg - even a 2% reduction difference is almost 2mpg. If a car only gets 20mpg ... you wouldn't even notice a 2% difference. So yes, big swings in "variables" can happen when you add the negative mpg detractors such as the drag/resistence of rain, snow, plus cold, short trips, new car, etc etc etc.