calculated vs. computer MPG - Please post your results

My number is different from your observation. My Gen3 (2015) was off 2.13% optimistic(78 fill-ups). My 2017 PP was 6.02% optimistic (54 fill-ups). My 2020 PP was 7.96% optimistic (6 fill-ups). My current 2021 PP so far with only 3 fill-ups is 8.69% optimistic.

 

My 2012 Prius II computer showed between 36-59 mpg as an average for every trip. I manually calculated it today and was able to go 597.5 mi. and only use 9.2 gal. Which comes to an incredible 65 mpg! Ambient temperature was anywhere from 32°F to 70°F.

 

Not too shabby How many miles on the engine?

65.3 mpg from the last 9,939 winter miles driven, almost at 200,000 miles on the engine.

 

199,000 miles. They are mostly highway miles, though. She still runs and drives like brand new.

 

Well that's mighty good! I just went on a 248 mile round trip Sacramento to San Francisco and computer said it was 44.5mpg; while calculated by fill up was 42.75mpg. Around town the computer is usually avg 35, so I would have confidence on a highway trip to go nearly 500 miles on a tank.

 

46.5 on the last 2 fill-ups. 2014 - 3. pretty much all highway driving.

 

What speed do you drive? 60mph? 65mph? 70mph? 75mph?

 

Mostly 70mph, not flat either. It's a nice hill country road to work.

 

computer was reading 48.5

 

How do you guys calculate your miles per gallon by hand and computer? I use a device called Savy Driver and the app calculates the MPG for me. So I can give you three calculations for my 2013 Toyota Prius Two.

 

Fill up. Reset "A" trip meter. Drive 200+ miles. Fill up. Divide the miles by the gallon
amount to fill the tank. Like: 250 miles driven divided by 5.2 gallons equals 48.0769231 MPG.
Or, 48.1....

 

I do this, but for extra security also record the odometer number. The latter displays for about 30 seconds whenever you turn the car off. Keeping a mpg log, I record the odo number at each entry, and subtract the previous value, and check that it matches Trip A.

If you're trying to record every fillup but forget, and/or if something like a battery disconnect happens (which will reset trip A to zero), you're covered. As long as you hang onto your gas receipts for a while, you can recover: moosh together two fillups for example.

 

I write down the mileage, trip miles, gallons, amount spent, Est. MPG's and Actual MPG.....
I have log books....

 

2015 Prius base model, took a little day trip with my family from San Jacinto, CA to TJ/Rosarito, B.C. 260 miles round trip, including 1hr 36m in idling at the border crossing. Used 5.833 gallons- 44.5 mpg, computer projected 47.6. Very happy considering lots of hills to and from Mexico. I generally set the cruise at posted speed limit, or 65mph, whichever is lower. Did lower to 60 mph on the steeper grades, or as traffic dictated.

Very impressed with a 7 year old salvage title car. Bought it as a “beater” (car is overall in decent shape, doesn’t stick out in a parking lot as being salvage) and it’s quickly become our go to car. Easy to park, comfortable, and the a/c is the best of any car I’ve ever owned by far. Should have bought one years ago!

 

Family emergency necessitated a trip to see my family in Napa. Got 46 mpg there (48.xx according to onboard computer) and 49 mpg on the return trip (52.xx according to onboard computer). I was really going for 50 mpg on the way home but I guess I have a goal for next trip

2015 Prius 2, me, wife, two kids, luggage for three days for all of us, various odds and ends. Still very happy. Car needs an audio upgrade, but other than I’m happy. I was in the fast lane the whole way up the grapevine and car made it up no problem. I was a little nervous it wouldn’t be able to. Obviously it’s not a race car but had no issue maintaining the 65+ traffic dictated to be in fast lane. Pretty sure I could have done 80.

 

hi. i have auris hybrid 2015 with new hybrid battery and new ac/dc converter, last month my computer average was 3.5l/100 km but in real time it was close to 4.0l (maybe more), i can't anderstand this but this is reality.

 

My 2010 Gen 3 is now at 114,859 miles. 325 fill-ups, total mpg is 44.9 over the lifetime of the car. The on-board computer has an ever changing error reading about 6.31% too high.

Fuelly.com is a place you can enter your fill-ups and it will keep track of everything for you. I do that, but I also have my own spread sheet.

Outside temperature can affect your mileage greatly, because the traction battery is not as efficient during cold weather. Also tires, inflation, how you drive, where you drive, etc.

I usually drive the speed limit (more relaxing, except on freeways in California or Illinois, where people drive crazy). The Prius has no trouble keeping up with traffic. It has no trouble going up mountains (I pass others, though I see my mpg goes down, but it's still way higher than theirs!), and I have never had trouble in snow (though if it's deep, I just stay home). The Prius is by far the best car I've ever owned.

 

I bought my 2010 Prius in February of this year, it had one owner prior and 140k odd miles on it.
I've tracked almost all of my fillups (about 30 over 8 months and 10.8k miles), and I ran a battery health test on it a couple months back.

The battery is a little above 50% health, so eventually I'm looking to probably update that. But for now the mileage is still holding pretty strong. I also replaced the front strut towers in September, and put some injector cleaner through it around the same time. Both things combined seemed to up my average by a few MPG.
It's fluctuating frequently with how far off it is, as low as 2% and as high as 9%. Over the course of my ownership it's calculated a 44.0875 mpg rate with an actual of 41.953, and averages being off by 5%. I'm curious to see how a new battery would help that, but the money I was setting aside for that went towards my deductible and a new catalytic converter

 

All gasoline comes through the same piplines and is loaded into tseparate large tanks for each brand.
The difference is in the blend of additives.
The blends you see at the pumps are blends from two tanks in a tank truck
I get significantly better mileage from Sunoco, -- enough to justify going out of my way.
I bought a charity Prius with 189K milles that was getting 41 mpg. additives cleaned it up inside and I have no difficult with 45.
Although I have gotten 50++ in flat land.
BAR sealant seamed to eliminate overheating Rislone seemed to get rid of an EGR model.
Next will be plugs and coils, and then maybe battery.

 

Apart from reading like fractured auto-translation, if you're dealing with head gasket failure thus it's not likely to last longer than a few months, and will mess up everything else in the coolant circuit.

What's the miles?