Calculated MPG vs. Indicated MPG of the c - Please post your results

I filled up for the second time today at 1,267 miles. This was 5 miles after the low fuel warning light came on. This time I filled to the top. Here are my cumulative fuel consumption stats:

I have driven 1,164 miles since I topped the tank after I got it from the dealer- 103 miles. I have put in 6.158 and 8.825 gallons for a total of 14.983 gallons. I calculate my cumulative MPG at 77.68 which is pretty good for mainly city driving.

I pay attention to the displayed MPG on individual trips and I have hit 80 plus on several occasions. I have been driving in ECO mode exclusively and glide a lot. Plus we have warm weather down here in South Florida which helps.

 

^78 mpg cumulative is earth-shattering (well beyond "pretty good," IMO ). Can't believe no one has responded to your results yet.

Finally filled it up for the second time today, and here are my comparatively disappointing results:

Date: 4-26
Miles driven: 558
Gallons Pumped: 9.168 (single top-off)
Hand-Calculated MPG: 60.9
Displayed MPG: 64.4
Tire Size / Wheel size: standard
Tire Brand / Model: stock
Tire PSI (Front / Back): 42/40
Seasonal Conditions: A/C used on a few days when temp rose well above 90.
Commute Length: n/a
Hypermiling Techniques: regenerative braking mainly
Other: More than a handful of trips under 5 miles means there is a lot of room for improvement. I only went on the interstate once. Most driving was done in city conditions and a state highway (30-50 mph). Additionally, I am a sucker for using cruise control and tend to drive right around the speed limit or under in the right/slow lane when traffic is light. Finally, I was not in ECO mode for the majority of this tank, if not for the totality. As expected, when driving with the same technique, the mode chosen seems to ultimately make little difference in fuel consumption, though it might have a bigger impact with excess A/C usage.

It seems the single topoff method is not providing me with accurate results on the display. I might try 2 topoffs on the next fillup, but I don't want to risk damage to the bladder.

 

Prius c does not have a bladder tank.

 

Whatever it has then. I'm pretty sure it's a charcoal filter, which could be subject to damage from the same mechanism (overfilling).

 

3rd fill up and my average was 43.4 mpg . The computer read 45.2 mpg Again, this is with 3 occupants, the driver(me) weighing in at 300lbs, a/c running, windy everyday. Trips are 10% highway and 90% city. City route is routinely 7.5 miles round trip.

 

Year of vehicle: 2012 Prius C
Date: 4/26/12
Miles driven: 510.2
Gallons Pumped: 8.987
Hand-Calculated MPG: 56.77
Displayed MPG: 59.2
Average Speed: 39mph (I think)
Tire Size / Wheel size: 15"
Tire Brand / Model: Standard for Prius C
Tire PSI (Front / Back): Not sure, haven't checked since I received the car.
Seasonal Conditions: (please include A/C usage and temp setting if applicable): Spring weather, with morning temps averaging between low to mid-40s, to low 50s. Daytime temps getting into the high 50s, to mid 60s. I used the A/C on occasion (maybe 15-20%), but tried cracking the windows when traveling slower than 40mph. Also turned off the A/C after it was cool enough in the car.
Commute Length: Roughly 60 miles, round trip. I average about 70 miles in the car most days. While I drove on the highway 3, or 4 times, for maybe a total of 50 to 60miles, I switched out to mostly back roads about halfway through my first week of commuting.
Hypermiling Techniques: Eco Mode 99% of the time. I switched between the Eco Score and the Energy Use screen throughout. I attempted, with some success, to use the pulse and glide method, but mostly relied on regenerative braking. Because the car is so light, I'm finding it difficult to maintain a nice long glide. This is something I've been able to take more advantage of in my father's 2009 Prius hatchback.
Other: (this could explain why a tank was bad or good or other unusual conditions like a rain storm, new tires, lots of short trips, etc.): Nothing else I can think of off the top of my head. I don't think I will do as well with my second tank, since I was forced to travel nearly 150 miles so far on the highway. Also, since I had my whole family with me, I used the AC almost the whole trip. I've gotten better mpg on the back roads than my first tank, but the highway average of about 54.5mpg (displayed), will probably bring my actual calculated mpg down a bit.

 

^That last bit is the easiest part, just a copy/paste.

 

Just got my Pc3 on Saturday. Have a forty mile trip I use for test. It's a mix of urban/suburban and freeway. Saturday averaged 56.1 mpg per display. Sunday, I set the tires to 40/38 and put in a lower grille block. Same trip, same time and weather, averaged 60.2. When I get down to half a tank, I'll fill up and check figures--maybe next weekend.

All the best.

 

I actually figured it was super easy, but just never bothered to look into it...I'm lazy that way.

As you can see, I've fixed my laziness and actually added fuelly.com to my signature. Thanks for motivating me.

 

Third tank down..best one so far...

Year of vehicle:2012
Date:5/2/12
Miles driven: 512.9
Gallons Pumped: 8.83
Hand-Calculated MPG: 58.1
Displayed MPG: 59.2
Average Speed: 25
Tire Size / Wheel size: 15"
Tire Brand / Model: Turanza EL400 02
Tire PSI (Front / Back): 43/40
Seasonal Conditions: little AC use...nice temps in Columbus, OH
Commute Length: 5 miles each way to work....some other longer trips also..
Hypermiling Techniques: Pulse and Glide
Other: None

 

Year of vehicle:2012
Date:5/3/12
Miles driven: 455
Gallons Pumped: 8.08
Hand-Calculated MPG: 56.3
Displayed MPG: 61.0
Average Speed: -
Tire Size / Wheel size: 15"
Tire Brand / Model: Factory
Tire PSI (Front / Back): 40/38
Seasonal Conditions: ~60-70F
Commute Length: 74 miles (round trip), 94% Hwy.
Hypermiling Techniques: Pulse and Glide
Other: None

 

Quick update.

My second fuel up.

Date: 4/2/12
Miles driven: 506.6
Gallons Pumped: 8.687
Calculated MPG: 58.317
Displayed MPG: 60.0
Average Speed: - (reset the trip info. before checking...)
Tire Stuff: Same as before (still haven't checked my tire pressure)
Seasonal Conditions: mid-40s to high-50s. A few days of rain. Minimal AC (Maybe 100 miles of it with AC on, mostly because my whole family was with me).
Hypermiling Techniques: Pulse and Glide. Regenerative Braking.
Other: That's all I can think of this time.

 

3rd fill up

Year of vehicle:2012
Date:02may12
Miles driven:444.3
Gallons Pumped:8.252
Hand-Calculated MPG:53.84
Displayed MPG:55.8
Average Speed:
Tire Size / Wheel size:175/65, 6.5x15 alloy
Tire Brand / Model: Turanza EL400 02
Tire PSI (Front / Back): 36/33
Seasonal Conditions: (please include A/C usage and temp setting if applicable) a/c on maybe 50%, set to 73*
Commute Length: 13 miles one way
Hypermiling Techniques: paying attention to HSI gauge, car set to "normal" mode vs ECO

 

I posted in a differnt place. My receits say i am getting 45MPGavg but my guage says 47 hiway 51 city

 

Year of vehicle:2012
Date:9/5/12
Kilometres driven: 842 or 523 miles
Litres Pumped: 31.994 or 7 gallons
Hand-Calculated L/100km: 3.79 or 62mpg
Displayed L/100km: 3.8 or 61.9mpg
Average Speed: -
Tire Size / Wheel size: 15"
Tire Brand / Model: Factory
Tire PSI (Front / Back): unknown (Dealership levels)
Seasonal Conditions: ~60-70F, 10-18 degrees Celsius
Commute Length: 44 km (round trip), 94% Hwy.
Hypermiling Techniques: Gliding, Careful driving, Conserving momentum, Hill techniques
Other: Drove 250km highway, the rest city

 

From what I am reading so far it seems that the MFD of the Prius C is about 2MPG off, or when the MPG is around 45-55, 4-6% - that is very similar to the Prius 2010, and from what I am reading, also of the Prius 2012. There some exceptions where it is actually "spot on" or sometimes where I read the error is well beyond 6% on a single tank. But on average I would say that 5%-6% is error average - don't you think?

It makes sense that if Toyota has sw/hw that works consistently well, with 5% that most public does not care about, they would not change it between models.

At least we know that it is constant - it didn't get better towards 0%, but not even got any worse.

Thanks to everybody reporting their stats!

 

I can confirm after over 71,000 miles the computer
generated mpg over reads 2.5-4 mpg.

In summer it appears the computer is less off; in the
winter it appears to over read more.

My last fill up was only 1 mpg off (warmer weather). Now for the last 2,000 miles it has been off 3 mpg over read. I just
compensate for it, but I would like to have it read at least
99% accurate....

 

Year of vehicle:2012
Date: May 8, 2012
Kilometres driven: 516 miles
Litres Pumped: 8.78 gallons
Hand-Calculated L/100km: 58.77 mpg
Displayed L/100km: 59.8 mpg
Average Speed: -
Tire Size / Wheel size: 15"
Tire Brand / Model: Goodyear Assurance
Tire PSI (Front / Back): unknown (Dealership levels)
Seasonal Conditions: ~60-70F, some Sun, some Rain
Commute Length: 74 miles (round trip), two lane
Hypermiling Techniques: Gliding, Careful driving, Conserving momentum, Hill techniques
Other:

 

Fourth tank down..They just keep getting better and better. I have attached some summary stat pics of this tank and the stats since I have owned the car...

Year of vehicle:2012
Date:5/13/12
Miles driven: 550.2
Gallons Pumped: 9.22
Hand-Calculated MPG: 59.7
Displayed MPG: 60.9
Average Speed: 26
Tire Size / Wheel size: 15"
Tire Brand / Model: Turanza EL400 02
Tire PSI (Front / Back): 43/40
Seasonal Conditions: little AC use...nice temps in Columbus, OH
Commute Length: over 50% highway on this tank
Hypermiling Techniques: Finding that I can travel above 42 mph and with the ICE on with low RPM's and catch the sweet spot of 75-100 MPG...Works great!
Other: None

 

This is my 3rd complete fuel-up. The mpg display has continued to show about 4% higher than the calculated values.

Year of vehicle: 2012
Date: 5/12/12
Miles driven: 480.4
Gallons Pumped: 7.80
Hand-Calculated MPG: 61.59
Displayed MPG: 63.9
Average Speed:
Tire Size / Wheel size: 175/65 15
Tire Brand / Model: Goodyear / Assurance
Tire PSI (Front / Back): 35/33
Seasonal Conditions: pleasant MI spring--no heat or A/C
Commute Length: 22 miles-- 50/50 mix of 55 mph highway and city streets
Hypermiling Techniques: P&G etc., all miles in Eco Mode

Other: This tank included two 85 mile trips that included freeways as well as stop & go city traffic. Overall, it is easier to get mpg over the EPA numbers with the "c" than it is with the 2nd generation (2008) Prius. (At least that is my current opinion. )