Almost time for the first fill-up

It's winter. Cold temperatures decrease MPG's. You have 17" rims, that lowers mpgs. If you've been driving through snow/rain/wind, that will lower MPG's. You are new to the car, that will lower MPG's. Your car isn't broken in, that will lower MPG's.


Your displayed average is 45.6 mpg, likely you will find you have a calculated value around 43 mpg. There are sticky threads on the site about why mileage is lower in the Winter that covers many items in the first paragraph and others (tire pressure, etc). There is also a nice video on driving the Prius that you should check out already.

Don't fret too much. Come summertime, you'll be singing the praises of the car.

 

So far from what've read here 1 bar = 1 gallon. So 300 miles / 7 gallons = 42.9 mpg. That's a perfectly acceptable number for a Prius. Keep in mind, winter mileage is lower than summer mileage due to the cold. Also, if it's your first tank, you can't be sure the dealer filled the tank completely. They might have filled enough to show full as you drive off. We don't know. Basically, what you have is on the low side of acceptable and chances are good that it will rise at next fill up.

Oh right, manual says break-in period is first 500 miles.

 

Once you fill up, a decent rule of thumb is that you can drive about 10x the displayed MPG and still have about 1.5 gallons of gas left in the tank. Thus, on your next tank, if you had a displayed 45.0 mpg, you could drive 450 miles, fill it up and the car would take roughly, 10.5 gallons (+/- 0.2 gallons) of gas. Drop dead empty is very close to 11x displayed. I wouldn't push it to 11x. Regardless of when you fill up, you will be using regular unleaded and less amounts, so you won't be paying the much higher price that you did with the Subaru.

Our climate in the Bay Area is a bit warmer. I routinely drive 650 - 700 miles between fill ups in the summer, but in the winter, I'm closer to 550 - 600 miles per tank. Colder temps and winter blend gas are the main culprits.

 

By your own numbers you will get right around 430-450 miles on this tank easy and then you will fill up with about 9.9 gallons or so.
So you will go almost the same as your Impreza except with 6 less gallons. figure that 6 gallons would get you another 250-275 more miles... so even on your lower mpg with winter temps and on 17" wheels you are crushing your old car.
Always have to factor in that much smaller gas tank.

 

I am also a recent owner but chose not to go new because there is no reason to buy a new car. The dealer filled it to maximum on December 31 and by January 18, I was very near empty.

Driving technique is huge for this car. Out of the box a Prius sucks if you drive like a regular car; hammer down to accelerate, drive it fast, and don't care. Technique is very important especially for winter driving. I finally settled into a technique of slow acceleration, mixing use of the battery and ICE, better regenerative braking, and finally seeing 50 MPG again and rising every day.

Accelerating slowly may not be your cup of tea or the driver behind you including driving 10-15 miles per hour below the speed limit (a limit after all as in ... go no faster than _____) but doing so with alternating cycles of battery - ICE - battery with no highway driving at all and a 15 mile commute in traffic to boot has shown me promise in this little vehicle that could.