2015 Prius gas mileage way worse than my old 2008

Kk but every trip is different up her in wa/or nothing but roads with constant tight curves and hills

SM-N920V ?

from motel to work mostly uphill I'll do same for after work

SM-N920V ?

 

	trip meter	miles	MPG	mph	gals	time
1	A	27.9	45.9	50	0.6078	0.558 hr
2	B	27.3	46.9	52	0.5821	0.525 hr
3	A-B	0.6	23.3	18	0.0257	0.033 hr (1:59 min:ss)

• observed - bold
• calculated - normal font, derived from obserations

It looks like Trip A was reset from the parking place and Trip B reset about 6/10ths of mile down the road. The difference is the 'cold start' over head for 0.6 miles or about 2 minutes into the trip. However there are several observations about how expensive a cold-start is to Prius metrics. Now there are some mitigations:

• Accelerate as fast as possible without racing the engine for the first 45 seconds . . . gently.
  
• For next 1-2 miles, use "N" at every opportunity to minimize fuel burn while the engine warms up.
• When "blue" light goes out, drive normally as the engine has passed 40C and most efficiency modes are enabled or will be within seconds.

BTW, this is an excellent technique, reset one trip meter part way into the trip. The differences between the two trip meters gives the cold-start overhead.

I'm looking forward to adding the evening trip metrics.

	trip meter	miles	MPG	mph	gals	time
1	A	22.8	42.4	40	0.5378	0.570 hr
2	B	22.2	44.9	42	0.4944	0.529 hr
3	A-B	0.6	13.8	15	0.0434	0.041 hr (2:28 min:ss)

The cold soak was 24:29 - 7:30 ~= 14 hours.

• observed - bold
• calculated - normal font, derived from obserations

Bob Wilson

 

SM-N920V ?

In morning first 10-15 miles are different degrees of uphills only.... soooo I tried

SM-N920V ?

Want me to do the same tomarrow for my 6 tanks of fuel I'll be burning up this weekend lol

SM-N920V ?

 

First off, you've done an excellent job. The data is clear and hopefully my sums make sense. But since you asked:

• route - especially with Google Earth or Google Map so we can look at terrain, speeds, and altitudes.
  • GPS recording? - we can handle the translations later. <GRINS>
• weather - winds, temperature, and precipitation.
• constant speed segments - cruise control on flat terrain, at least 10 miles any given speed (will use photo of trip meter for metrics)
• compare mile markers to trip meter for 50+ mile segments (any speed) to calibrate mph, distance, and MPG
• heater, air conditioner, lights status - vehicle overhead

Bob Wilson

 

GPS recording? Should I be worried lol

SM-N920V ?

Stevenson wa to Cheyenne wy

SM-N920V ?

 

Near Ogden, there is a flat valley at 4,200 ft with plenty of opportunities to do mph vs MPG metrics:




Bob Wilson

 

I know where you are talking about

SM-N920V ?



SM-N920V ?

 

Let me share some technology about tables:

	trip meter	miles	MPG	speed	gal	hrs
1	A	373.9	43.3	57	8.635	6.56
2	B	324.6	44.0	68	7.377	4.78
3	A-B	49.3	39.2	28	1.258	1.78

*table=head]
trip meter|miles|MPG|speed|gal|hrs
A|373.9|43.3|57|8.635|6.56
B|324.6|44.0|68|7.377|4.78
A-B|49.3|39.2|28|1.258|1.78
*/table]

"*" - "["

The table tags use paired "[" and "]". The rest is fairly straight forward.

Bob Wilson

 

It is too early to say ... 3 tanks could be outlier especially the first... check the tire pressure. I had a Gen2 and later a Gen3 10-12% better MPG ... I still have the spreadsheet to prove it ...

Also the driver characteristics of the Gen3 is slightly different takes some use to it. Also as someone already said the new tires accounts for a few % itself ....

 

OH WELL!!!! 68MPH (average) will NEVER give you 50+MPG unless all of those 300 miles is going downhill with backwind

 

Last round trip here he my trip meter

SM-N920V ?

It also has 6 hours idling while I slept over night so......

SM-N920V ?

 

ouch. that'll do it.

 

This helps a lot:

• 2309.7 miles / 38.3 MPG = 60.3 gallons at least 5 fill-ups
• 2309.7 miles / 57 MPG = 40.52 hours

A gentle reminder for all, to reset the "B" tripmeter, hold the steering wheel "trip" button down for 5 seconds. All of the numbers will blank out and it will start from zero. Regardless, the "6 hours idle while sleeping" helps:

• 40.52 hours - 6 hours at idle and 0 mph = 34.52 hours running
• 2309.7 miles / 34.52 hours = 66.9 mph

Using this chart:

• 38 MPG indicated is consistent with driving at 80 mph on a shirt-sleeve day
• 38 MPG is consistent with 70-75 mph at temperatures close to freezing
• 38 MPG is consistent with 65 mph into a 15 mph headwind.

RECOMMENDATION

1. Take a photo of trip meter when filling up.
2. Reset the trip meter before leaving station.
3. Report each tank photo of trip meter.
4. Use either "A" or "B" tripmeter for your tanks and the other one for specific segments (i.e., on the highway, around town, unusual weather) be sure to make a note for each segment.

Bob Wilson

 

Next few trips is only 3 hour drives

SM-N920V ?

 

I'd recommend documenting with either the "A" or "B" trip meter each segment. This will give more insights than a total. But at a minimum, do no more than a single tank on a trip meter as this hides particularly good or bad segments.

Altitude changes are also significant. Climbing to Nashville from Huntsville is a 3-4 MPH penalty which I get back on the return from Nashville to Huntsville.

I would recommend getting a SCANGAUGE or equivalent that can show the engine rpm:

• 0-3200 rpm - engine will be at peak efficiency 38%
  • 24x7 works great
• 3200-5200 rpm - engine will be less efficient, good but not in the 38% efficiency range
  • a couple of minutes is OK but over 5 minutes, time to back it down
  • Above 3200 rpm, the engine begins to run out of cooled EGR and has to start using fuel enrichment to keep the catalytic converter from burning up. This richer mixture also leads to more hydrocarbons in the exhaust that can 'coke up' the EGR valve and tube.

Bob Wilson

 

Well it will be a a week or 2 as I have to drive my truck due to the weather

SM-N920V ?

 

Any recommendations on a scangauge?

SM-N920V ?

 

The scangauge II is what I use because you can add XGUAGEs for custom data. It also give a way for true MPG although right-sized tires solved that for me years ago.

Bob Wilson

 

Right sized tires? What size you use?

SM-N920V ?

 

This is where I discussed the options: How to improve gas mileage in this situation? | Page 2 | PriusChat

I went with: P205/65R15

If you decide to try time, get just a pair for your front wheels. That won't cost and arm-and-leg and you'll get most of the benefit. Some folks don't like them but I have no problem with them.

If you like them the second pair is easy enough when the current tires get thin enough.

Bob Wilson