From a newbie, of course! I've had my car for about a month. When I first got the car I was filling up at two blips - over 410 miles - 8-ish gallons to fill. Now I am filling up at 1 blip - under 400 miles - still 8-ish gallons to fill. Why the mileage difference but still filling up at 8 gallons? Seems odd to me...
How cold has it gotten there in MA recently? When the car is warming up (the first 10 minutes, generally) the mileage is horrible - for me here in MN, i typically see mileage in the high 20's for the first 5-10 minutes before getting the 5-minute bars back up into the 50 MPG range. remember that a lot of the benifit the car can derive is from turning the ICE off whenever possible - when warming up from cold temperatures, it can't turn it off, so you burn more gas than you do durring the summer. There are some charts and spreadsheets and such floating around on here that show the temperature/mileage relationship over a number of years, and are pretty sweet. All the same, you're getting about 50 MPG, so it's nothing to worry about! *edit* ugh, i just saw my greenhybrid banner in my sig... i really need to add the last 6-7 tanks or so to bring that number up - current tank: 55 MPG!
You'll see posts about this all over this forum. The Prius in the USA has a bladder in the fuel tank. Depending on temperature, phase of the moon, and the alignment of the planets, the bladder will allow more or less fuel into the tank. You can never be sure how much fuel is left for a given number of pips on the fuel gage. You get an idea, but it's not exact. Tom
You may discover the tank has less capacity in cold weather due to the bladder. Also depends on what you mean by full. If I fill mine until the pump clicks off the first or second time I can be from approximately 1 to 3 gallons less than full. It seems to do better in warm weather because the bladder is more flexible. I almost never fill it clear to the top because it sometimes burps and runs out. I just use the MFD mileage it seems to be more accurate most of the time.
Whatever else, remember that when the last pip starts blinking it means that you must buy fuel immediately. You cannot safely calculate or assume anything about how many miles worth of gas remain.
