New 2013 Prius C, poor MPG

Over nearly 20,000 miles my average mpg is 47.2. I fill up every two days because my roundtrip commute is app. 130 miles. I don't want to risk a third trip because that would be pushing what I consider the limits of judicious driving. Most recently (past 10 fillups) I've been averaging 43.8 mpg so I'm putting in app. six gallons at a time.

 

Bought my Prius C in October 4 2013. Almost 5 months $505.57 and 6852.7 miles. Do the math and let's see if the Mpg's are accurate. 505.57 / 4 =126.4 galons of fuel. 6852.7 miles / 126.4 galons = 54.2 mpg's. The display says 48.2

 

When I got my C2 in Nov the tires were ~5psi low, luckily I caught it before I drove very far. I inflate the tires to take into consideration the expected temp, not the current temp. I add 1 psi per each 10 degrees F, so if it is 50F when I inflate them and it likely to go to 20F, I add 3psi to the spec. Since then I have refueled six times and have been averaging 48mpg in mixed city/highway, while the temp has been ~10 deg below norm for Ohio. The displayed mpg and calculated have been within 1mpg. I dress warm and minimize the use of the heater.

 

I usually get 500 miles before fill up. I live in a western oregon. it doesent freeze here much. I usually park in my garage until the last month, due to using garage to store some thing temp. the mpg on a prius c can vary a lot depending on how far you drive, how cold it is, what tire pressuer is. what speed you are driving. My trip to work and home is only 2.6 miles and cold temp drops mpg on that trip from 55mpg to 45mpg cold but in garage, and 35mpg a couple of times with frost and parked outside. once the car is warm the mpg in town climbs to 65-75 mpg. I have my tires at max sidewall rated pressure. and the speed zones I drive in are mostly 35mph or less.

 

how far do you drive? if you warm up a cold car and drive 2 miles your mpg will be bad. I think you said you put air in your tires what psi do you have them?

 

what does an 80s buick get. if you fill up at 8 gal then the buick gets average of 37.5. they must have a hwy mpg of around 43? I dont think so. The prius C gets great mpg in city driving. if you drive in city very far your mpg will be great.

I think you may be telling us a fib.

 

Im glad you got onto fuelly. That is the best way to keep track of mpg and see if you are doing better or worse than others with your car.

 

yes indeed....I wish I got your mpgs

 

I drive my car until the fuel bar blinks and then a little more no more than 20-30 miles. This usually gets my tank down so it takes a little over 8 gal to fill. this provides a similar fill up each time. I fill until first click, nothing special and never top off. I think consistancy helps me get more accurate mpg results. my tires are at 50 psi, I keep my upper and lower grill blocked until summer. I drive almost all the time in city where mph zones are 25-35 with a little 40-55. I find my biggest loss of mpg is short trips where I only get 45 mpg. on longer trips after engine is warm the mpg climbs way up there over 70 for like a 10 mile round trip.

Please describe your driving conditions and psi in tires ect.

 

I think its the hwy that is killing me, doing city driving esp when its warm is pretty spectacular unless its cold out and the car doesnt have time to warm up. A 60 mph on the hwy I think even its 55+ mpg. I just cant drive that slow since the posted speed limit is 70 mph and Ill get killed if I dont go at least 75 mph. Since half of my miles are on the hwy and it only gets 46ish that has hurt. I only had the tires set at the PSI on the door (32/34 I think) but just added air to 42 f/40rear. I may not keep it though as it seems to have noticeable made the ride more uncomfortable, I now feel every pothole/bump etc.

 

The easiest and most accurate way to know what mpg your getting is to .

#1 fill tank completely when it won't hold any more.
#2 set trip meter back to zero
#3 drive at least 100 miles
#4 stop at fuel station and fill up completely again.
#5 divide 100 miles (or how many miles that are on your trip meter) by the exact amount of gals of fuel you just put in the car. did your car hold 2 gal? You got 50mpg... 2.5gal? You got 40mpg ect ect ect This is a very accurate measurement. try this in different seasons and notice by fuel blends how it changes... it does ;-)

This will do several things. You can measure by full tank fill ups unless you plan to run your car completely out of fuel. Doing the tank to tank fill up although close is not accurate.
By following the simple steps above you will know in a day or two exactly what you are getting (granted you drive a min of 100 miles in a day or two) . Blend your driving in those 100 miles like you would normally drive... not just on freeway to rack up the 100 miles fast.

 

HWY speeds with cruise control on above about 68 mpg with get you in the 40s fast. at 80 mph with cruise probably low 40s. I can get 55+ mpg at 60 mph with cruise or dont use cruise at all and try to keep it out of the red, might speed up going down a hill or slow down going up but seems to work, I did this on a trip back from Georgia and kept it out of the red, speed varied between 60 mph and 85 mph but I got 55 mpg. its when it gets in the red that eats gas

 

Lol, HALF of those MPG's need to be fixed to MPH's

I routinely get 52-56 MPG going 65-73 MPH. Not always, but normally.

 

Hard to do it that way with fuel prices constantly fluctuating

 

I consistently have a 2 mpg discrepancy between the actual fill on the tank calculation mpg vs the computer. The computer is always about 2 mpg higher.

 

Understandable, but the post I replied to referred to more than one tank worth of fuel. WELL more than one tank, between 10-14 tanks. Undoubtedly MULTIPLE different price per gallon prices...

Yeah, that's higher discrepancy than some, less than others. Either way, drive a gps calculated route, and see how many miles your car says you went, bet it says you went less, aka your ACTUAL miles traveled will more likely than not match your computer's mpg reading if it's not in fact BETTER than what the computer says

 

Tank size I

Tank size does not matter. All vehicles are designed for a tank size to fit the size of vehicle for a reasonable range from the average driver and overall available space and to pass crash testing to name a few.

Never let your C sit to warm up cause you are burning gas and polluting for nothing. As soon as any engine has oil pressure you are good to go. Get the car up to around 35 to 40 mph put on the speed control and wait for warm air to roll out of the vents in cold weather. That is the quickest way for the least fuel burn to warm up the C unless you install a block heater but even then if you have it on to long the cost of electricity will be more than the gasoline used as above.

To get the high mpg that we get and others brag about, you must drive like there is an egg under your foot and use the ECO display. When there is no traffic behind you, keep the ICE from coming on as long as possible. Learn how to drive all over again. If you find your self with either a foot on the throttle or on the brake with no coasting or traffic anticipation inbetween you have not learned to drive this beautiful C. I took Nancy to volunteer this morning, round trip from our house, air conditioning on, cold start and 5 miles of the 13 miles was at 50 mph. Result 65 IMG. (A round trip negates elevation and wind direction effects if done without stopping in a short time).

 

[quotis true="Brad K, post: 2007323, member: 120001"]I consistently have a 2 mpg discrepancy between the actual fill on the tank calculation mpg vs the computer. The computer is always about 2 mpg higher.[/quote]
That is true for us as well and even our Mercedes cdi was 2 mpg high as well. Sounds like a conspiracy?

 

Never, never, never run the C out of fuel. The fuel lines are hand built for each C individually and you can damage the fuel system's vapor recover system to name a few. Be satisfied with filling to the first click at the nozzle of the same pump headed the same direction. There are variables you can not control like the density of the fuel and fuel pressure at the nozzle to name a few, so do not worry about them.quote="The Electric Me, post: 1955211, member: 50927"]Are you purposely being dense?
When or where am I or anyone saying run your tank out of fuel just to see how far you can go?[/quote]