Influence of speed, temperature, and weight on MPG

[odaigle]

Originally Posted by bwilson4web

The aerodynamic drag is proportional to air density and the velocity squared. Using the Wiki table:
Hope this helps.

Bob Wilson

This is very interesting data. However, from my understanding, the drag is proportional to rho times v^2.0 (rather than (rho * v)^2.0). Thus, shouldn't you divide the MPG by the drag rather than by the drag squared? Or I am missing something?

[orange4boy]

I think you may be underestimating electrical draw from the heater fan and rear defrost in your analysis. Also, the front defog setting runs the electric A/C to dry off the fog. The defog/floor setting does not use the A/C.

The rear defrost eats 1A at 300V in the NHW11. (300 watts) Add 20% for efficiency losses between the generator and battery and you have 1/2 horsepower.

Other electrical loads. 2003 NHW11.
Running lights: .12
Headlights: .57 A high beams .51 A low beams.
Brake lights: .37A
Rear defrost 1 A
Fan setting in amps: 1) .21 2) .34 3) .52 4) .65
Steering draws about 1A only while turning wheel, stopped, on gravel.

[Indyking]

Attached is a excel file with data from all my 35 trips collected from the 2010 Prius before I traded it. There are 2 sheets in the same file, one for data and the other one for charts. These are all 100% hwy trips that varied from 340-360 mile-long, mostly flat. It represents 12250 miles worth of data. I don't need this anymore and perhaps someone here may find it interesting. Some cells contain comments that can be revealed by hovering the mouse pointer over the marked place.

Cheers...

[Tom183]

Wow - your average actual MPG, during the coldest months of the year and running at highway speeds of 70+, came out to 44.7mpg.

Two of your trips were above 48mpg actual - MORE than the EPA estimate for highway.

I can see now why you were so hysterical - not.

[Indyking]

Originally Posted by Tom183

Wow - your average actual MPG, during the coldest months of the year and running at highway speeds of 70+, came out to 44.7mpg.

Two of your trips were above 48mpg actual - MORE than the EPA estimate for highway.

I can see now why you were so hysterical - not.

\
Oh dear, some of the less fanatic ones are already getting the idea, but some never will.

The MPG drop was just one of my concerns in the Prius and turned out to be the least one in the end. I drive a lot as you know, comfort is paramount in my case and the Prius cloth seat was killing my back. Interior quality, convenience, exterior looks… all that had a huge impact in my decision too.

Just try to accept the fact that the best mileage is not everything in a car, please.

Let me just leave you with a thought: You have the same Prius as I did... The Sonata 2010 limited price is pretty similar to Prius III considering MSRP with no discounts but, in reality, it is about 3-5K cheaper considering the current specials/incentives. I would rather have leather, heated seats, lumbar support, 17” wheels, moonroof, Infinity audio system with 10 speakers, fog lights, interior wood accents, shiftronic transmission (manual or auto depending on your mood), more interior space, way more comfort, better handling, real car power, way more quietness, solid interior with no rattles/creaks, 5 star crash ratings, radio display where I can actually see the whole name of the song, dual automatic climate control with auto heater that actually works... I mean... even if the Prius gave me 200 MPG and no winter drop, I would still toss it. My level of comfort now and in the past is just no comparable.

Think about it!

Ciao...

[usbseawolf2000]

Originally Posted by Indyking

...These are all 100% hwy trips that varied from 340-360 mile-long, mostly flat. It represents 12250 miles worth of data. I don't need this anymore and perhaps someone here may find it interesting....

2008 EPA test procedure produced 50 MPG number based on 48 MPH average. Your average fuel economy was 44.7 MPG. Your average speed was 65.5 MPH.

The faster you go, the less MPG you get especially above 55 MPH.

[Tom183]

Originally Posted by Indyking

The MPG drop was just one of my concerns in the Prius and turned out to be the least one in the end.

It certainly was not at first...

Originally Posted by Indyking

Let me just leave you with a thought: You have the same Prius as I did... The Sonata 2010 limited price is pretty similar to Prius III considering MSRP with no discounts but, in reality, it is about 3-5K cheaper considering the current specials/incentives.

Cherry-picking again... I didn't pay MSRP - sticker was $24500, I paid $23200 (before negotiating my trade-in). And this was before the recall fiasco. No doubt you paid less for your Sonata, but not much.

[kgall]

Originally Posted by Indyking

Attached is a excel file with data from all my 35 trips collected from the 2010 Prius before I traded it. There are 2 sheets in the same file, one for data and the other one for charts. These are all 100% hwy trips that varied from 340-360 mile-long, mostly flat. It represents 12250 miles worth of data. I don't need this anymore and perhaps someone here may find it interesting. Some cells contain comments that can be revealed by hovering the mouse pointer over the marked place.

Cheers...

Thanks for this information! I hope someone with better statistical chops than I have might be able to tease out the effects of speed vs. the effect of temperature vs. weight and other factors from this.

Hope the Hyundai meets your needs better. With the amount of driving you do, I can see your lumbar support issue.

In six months, you can let us know if you think Hyundai and Korea are going to eat the lunch of the Japanese carmakers, the way the Japanese ate the lunch of American and European carmakers for the last few decades.