[veggivet]

While waiting for my Prius to be delivered I've been checking out several threads relating to gas mileage. The numbers I've seen range from the mid 30's into the 50's. After a reasonable break in period, driving in winter temps at cruising highway speeds (75+/- 5 mph), what kind of mileage should I expect? My typical trip length is 30 to 40 miles. I plan on switching to synthetic oil at the first oil change (5,000 miles?), and will increase the tire pressure to at least 40-42 psi. The car will be garaged overnight (not heated but still a few degrees warmer than outside temp).If my mileage will only be in the upper 30's to low 40's, I would have to rethink my decisionas I would be giving up a lot in the handling department as I'm driving a MINI Cooper now. It gets about 31-32 mpg.
Thanks in advance for your responses.

 

[john1701a]

This document contains 2 graphs showing the efficiency variances throughout my 3 years of driving a 2001 Prius...

http://john1701a.com/prius/documents/Pr ... fetime.pdf

You can very clearly see how extreme of a dip Winter causes. You really can't expect much more than 40 MPG, even when after the Prius is broken in, in an extreme environment like Minnesota. But then in the Summer, efficiency will shot all the way up to 50 MPG.

So I would suspect the same will be true for my 2004 Prius, except the MPG will likely be a few MPG better.

These factors effect cause lower MPG in all types of vehicles, including hybrids:

- Cold air is more dense.
- Warm up takes longer.
- Winter formula gas is less efficient.
- Traffic conditions are different.

Then of course, you've got these other influencing factors:

- break-in
- oil level
- oil type
- tire pressure
- heater preventing the engine from shutting off

 

[efusco]

While waiting for my Prius to be delivered I've been checking out several threads relating to gas mileage. The numbers I've seen range from the mid 30's into the 50's. After a reasonable break in period, driving in winter temps at cruising highway speeds (75+/- 5 mph), what kind of mileage should I expect? My typical trip length is 30 to 40 miles.

Much of the key to your question is the speed and distance and winter driving. On a recent trip in my '04 of about 300 miles round trip the majority of which was freeway I maintained cruise control at 79mph. I'd estimate 70% of the distance was at that speed on gently rolling terrain. My consumption screen's 5 minute MPGs were basicly flat during the freeway portion. I averaged b/w 37-38 MPG. I have my tires at 44/42. I've checked the oil level. We had 4 passengers (two of which weighed only 70 lbs combined) and a little luggage.

I think you might be able to get 40 MPG or maybe a little better if the terrain is flat and you keep speeds closer to 75mph. And you'll probably jump to the mid-40s if you keep the speed under 70mph. Warm months, as mentioned, will be better.

I was disappointed (and am still a bit) in my mpg initially. But, I'm quickly learning how to drive the car most efficiently without really slowing down much or impeding other traffic. I, unfortunately, have to make a couple sub-10 minute commutes each day from a cold start and that really makes a hit on my mileage. When I can drive for more than 20 minutes I can usually start pushing the MPGs backup significantly and ultimately think I'll be very close to 48-50 mpg on a lifetime average...perhaps even better, but I doubt it once you figure in longer trips and higher speeds and other variables.

If you're only looking at this car for it's improved gas milage you will have a hard time justifying it. There are more economical vehicles out there, no question about it. BUT, if you need a versatile, economic, enviro-friendly, mid-size car packed with technologic features equivalent to a luxury car then you should consider it most carefully.
--evan

 

[gene godefroid]

No question with my 03 having the brake problem, the sudden drop in mpg tipped me off that something was wrong. Hope to get my car back today, and looking forward to much improved MPG...here's my data since I first bought the Prius...
DATE OD FILL gal. $ paid mpg accum mpg miles driven $/m pr/gal #days
01/02/03 138
01/10/03 581 9.628 $13.37 46.01 443 $0.0302 $1.3887 8
01/17/03 1021 10.251 13.25 42.92 44.47 440 $0.0301 $1.2926 7
01/27/03 1460 9.211 11.78 47.66 45.53 439 $0.0268 $1.2789 10
02/06/03 1927 9.491 13.28 49.20 46.45 467 $0.0284 $1.3992 10
02/14/03 2396 10.059 14.27 46.62 46.48 469 $0.0304 $1.4186 8
02/24/03 2733 7.702 10.70 43.75 46.03 337 $0.0318 $1.3892 10
03/03/03 3146 8.999 13.40 45.89 46.01 413 $0.0324 $1.4891 7
03/12/03 3632 10.625 16.25 45.74 45.98 486 $0.0334 $1.5294 9
03/17/03 3830 3.001 4.74 65.98 48.20 198 $0.0239 $1.5795 5
03/18/03 4272 10.405 18.72 42.48 47.63 442 $0.0424 $1.7991 1
03/22/03 4516 5.337 8.00 45.72 47.45 244 $0.0328 $1.4990 4
03/23/03 4894 10.228 16.25 36.96 46.58 378 $0.0430 $1.5888 1
03/29/03 5326 8.795 12.39 49.12 46.77 432 $0.0287 $1.4088 6
04/09/03 5836 9.048 11.39 56.37 47.46 510 $0.0223 $1.2588 11
04/18/03 6243 8.261 10.48 49.27 47.58 407 $0.0257 $1.2686 9
04/30/03 6744 10.091 13.11 49.65 47.71 501 $0.0262 $1.2992 12
05/10/03 7214 10.381 12.97 45.28 47.57 470 $0.0276 $1.2494 10
05/15/03 7426 3.734 5.60 56.78 48.20 212 $0.0264 $1.4997 5
05/15/03 7778 9.071 12.60 38.80 47.96 352 $0.0358 $1.3890 1
05/19/03 8173 9.400 14.02 42.02 47.38 395 $0.0355 $1.4915 4
05/19/03 8593 11.104 14.87 37.82 46.90 420 $0.0354 $1.3392 1
05/27/03 9112 9.189 11.29 56.48 47.36 519 $0.0218 $1.2286 8
06/08/03 9640 10.698 13.68 49.36 47.45 528 $0.0259 $1.2787 12
06/14/03 9994 5.768 7.55 61.37 48.05 354 $0.0213 $1.3089 6
06/20/03 10406 8.677 11.44 47.48 48.03 412 $0.0278 $1.3184 6
06/21/03 10728 7.302 10.43 44.10 47.87 322 $0.0324 $1.4284 1
06/27/03 11261 10.017 13.51 53.21 48.08 533 $0.0253 $1.3487 6
07/11/03 11743 9.467 12.68 50.91 48.18 482 $0.0263 $1.3394 14
07/24/03 12282 10.850 15.08 49.68 48.24 539 $0.0280 $1.3899 13
08/01/03 12793 10.067 13.38 50.76 48.32 511 $0.0262 $1.3291 8
08/11/03 13169 8.619 11.37 43.62 48.17 376 $0.0302 $1.3192 10
08/19/03 13607 10.180 14.45 43.03 48.00 438 $0.0330 $1.4194 8
09/03/03 14026 8.749 12.41 47.89 48.00 419 $0.0296 $1.4184 15
09/11/03 14455 9.779 13.58 43.87 47.87 429 $0.0317 $1.3887 8
09/23/03 14940 10.259 14.76 47.28 47.86 485 $0.0304 $1.4387 12
10/02/03 15359 8.939 10.99 46.87 47.83 419 $0.0262 $1.2294 9
10/16/03 15771 9.547 12.59 43.15 47.70 412 $0.0306 $1.3187 14
10/29/03 16249 9.441 11.89 50.63 47.78 478 $0.0249 $1.2594 13
11/11/03 16661 9.302 11.90 44.29 47.68 412 $0.0289 $1.2793 13
11/19/03 16882 5.382 7.26 41.06 47.52 221 $0.0329 $1.3489 8
11/26/03 17240 9.519 12.08 37.61 47.27 358 $0.0337 $1.2690 7
366.573 503.76 46.65 47.36 17102 $0.0295 $1.3742 315
Gene

 

[christensenma]

disappointing fuel economy

With a 2002 and mostly short trips (we live on an island where the longest trip is about 15 miles and the speed limit is 45), some on dirt roads and we seem to get 45 mpg in the winter and 50-55 in the summer.

Highway I've got to think that going the speed limit will improve economy. Wind resistance increases to the power of 3 I think. Still, we get close to 45 mpg.

The 2004 should be more slippery. Also, if you keep the display on the fuel usage, you will start to modify your driving.

 

[frenchie]

Wind resistance increases to the power of 3 I think.

Drag force increases like the square of the speed, and so does the energy needed to overcome this force over a given distance.

 

[Wildman]

You're both right... kinda

DRAG (a force) increases with the square of speed... POWER required to overcome drag increases with the cube of speed. Drag is measured in pounds while power is a measure of the rate of change of a force, (ft pounds per second) usually measured in horsepower.

The reason your mileage doesn't vary that much is that fuel consumption isn't linear with respect to engine/motor RPM. Look at the slope of the power vs RPM curve and relate that to an RPM and that to a speed.

 

[ken1784]

SPEED vs MPG

FYI,
Following is some rough data about SPEED vs MPG table from Japanese owners.
Your data may be varied. It might have 10% deviation.

70km/h 30.0km/L = 44MPH 71MPG
80km/h 27.5km/L = 50MPH 65MPG
90km/h 25.0km/L = 56MPH 59MPG
100km/h 22.0km/L = 62MPH 52MPG
110km/h 18.5km/L = 69MPH 44MPG
120km/h 14.5km/L = 75MPH 34MPG

 

[Guest]

Hi Ken1784:

___Probably a dumb question but was that data collected from the 04 or the 01-03? If this data was collected from a variety of 04s, they may not even be broken in yet! I do like what I am see at 56 - 59 mph

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:1gxo2679][email protected][/email:1gxo2679]

 

[NH Prius]

happy two weeks in

I've only had my '04 for a couple of weeks, but I'm pleased with mileage so far on longer trips. As others have noted, short trips around town in cold weather don't yield outstanding results, but longer 50+ miles between 40 and 60 mph have yielded between 50 and 53 mpg. I, for one, am most pleased!

 

[ken1784]

Re: SPEED vs MPG

Hi xcel,

The data is from various 2004 Prius owners mixed brand-new and after broken in.
Your data could be varied...temperature, wind direction, altitude, tire pressure, engine oil type, fuel type, weight, etc, etc...
You maybe happy if your data is between +/- 10% of the data.

 

[Guest]

Hi Ken1784:

___Thank you for the info. There is still hope yet for 60 + mpg then with an all synthetic oil change-out, high pressures in the GY Integritys, warmer temps, and maximum mileage driving techniques.

___Thanks again.

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:92atyc0z][email protected][/email:92atyc0z]

 

[Joel]

As my break in occurs, I've noticed improved fuel economy. Still not convinced about switching to synthetic though.

Hi Ken1784:

___Thank you for the info. There is still hope yet for 60 + mpg then with an all synthetic oil change-out, high pressures in the GY Integritys, warmer temps, and maximum mileage driving techniques.

___Thanks again.

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:3kbv0rt5][email protected][/email:3kbv0rt5]

 

[patrickg]

Would someone please explain to me what big changes are expected to occur with break in that would significantly improve MPG? I mean what is the source of the big change?

In the olden days "break in" was a big deal because of the way engine parts fit and the properties of the lubricants in use. Special break in oils were common. When these were drained there was a lot of fine metal in them showing that the parts had been honed down.

Now, about the only concesion to break in oil is to run the MFG recommended lubricant AS BREAK IN OIL and then go to synthetic or whatever if you choose to do so.

I do understand the "vary your speed", "don't drive too fast", and "do not lug your engine" admonishments as parts wear to fit each other better, establishing good working clearances prior to allowing max stress. Note: I don't think it is likely you will "lug" a Prius.

What I don't understand is that, given the manufacturing tollerances in todays engines, what coild be the source for a really significant MPG improvement as the vehicle breaks in.

In a Prius, I suspect a good part, not all, but a significant contributor of this break in mileage boost, is breaking in the driver.

Another aspect of variable mileage: Someone mentioned cooler winter air as a source of reduced mileage because the air is denser. BUT increased air density INCREASES horse power output. It increases drag as well but my experience has been that the increase in HP has always been significantly greater than increased drag. Older hot rodders will recall that their "ride" always performed with more pep after a thunderstorm with cool dense air. Similarly, density altitude (a measure of air density) effects recipricating aircraft engines, reducing available HP with reduced density making for longer takeoff rolls at higher equivalent altitudes. Drag is reduced as altitude increases but acceleration on take off is not helped by reduced density because engine performance is the larger effect.

Intercoolers on high performance turbo boosted engines are there to cool the air taken into the engine.

I'm not saying Prii might not get reduced overall mileage at low temps, just that it isn't because increased air density reduced the engine HP.

Pat

 

[john1701a]

> Would someone please explain to me what big changes are expected to occur with break-in that would significantly improve MPG?

Engine break-in is only a small part of the equation.

It's the other moving parts that make a contribution to efficiency too. For example, the bearings in the wheels will loosen up. That will reduce resistance allowing easier movement. But that doesn't happen as quickly as engine break-in does.

 

[patrickg]

Thanks John, I was too focused on the engine. Of course there are other mechanical contributors.

We are in agreement that the engine is not the whole enchilada. I personally think that in the case of the Prius, driver break in is quite important.

Thanks again for getting my head out of the engine "box."

Pat

 

[RSnyder]

Driver "break in" is certainly part of it, but it's too abrupt (at least it was for me) to be the big contributor. My theory is that the computers train to the characteristics of the engine and particularly of the battery during this time. The battery is probably not used to its best efficiency before the computers are trained because they probably vary the state of charge a lot just to find out what it really is and how the battery responds.

Just guessing, don't hold me to this.

 

[jfellows]

04 Prius Mileage

I've got about 2,000 miles on my 04 Prius. I drive mostly around town witha mix of freeway and sidestreets. I have taken a couple of trips at 65-70 mph. I keep meticulous records for tax purposes, and I am getting roughly 40 MPG (39-43). Freeway or town driving doesn't seem to make any difference. :shock: I've read other reports that mileage on the pre-04 was typically 40 in the Winter ( Minnesota). I hope the mileage improves with time and temperature.

 

[Henry]

Forget it, guys; you are never (repeat "never") gonna get the EPA mileage ratings in *any* car! Even less likely that you will get better city than highway mileage in the Prius. The EPA (=Toyota-provided) numbers are bogus for real-world driving. I have come to accept that 46 mpg (actual calculated) is about the best I am going to do in my '02. Sure is better than 15 mpg in my '91 Exploder!

Lie back and enjoy it!

 

[tjl]

Forget it, guys; you are never (repeat "never") gonna get the EPA mileage ratings in *any* car! Even less likely that you will get better city than highway mileage in the Prius. The EPA (=Toyota-provided) numbers are bogus for real-world driving.

Beating the EPA estimates is not difficult in many cars. You just have to drive in an economical manner. For example, when a light ahead turns red, get off the accelerator and coast instead of racing to the light and slamming on the brakes. And generally try to avoid lots of speed changes (don't tailgate; tailgating forces you to change speed a lot when the vehicle ahead changes speed, and is unsafe).