Quote:
Originally Posted by aerohead
I'm the nut-case who guestimated the Cd 0.116 requirement.
I'd be happy to revisit the calculations.
I do not have an accurate:
1) frontal area
2) all-up average travel weight
3) tire manufacturer
4) tire model
5) inflation pressure
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6) I was presuming zero hybrid function, just constant speed driving, only on the engine ( according to Emission Analytics, your hybrid system increases composite mpg by 48% because of regen ). It's impossible to calculate anything if the hybrid assist is affecting performance.
7) I'm driving a 2009 Prius right now. It's never indicated above 43.3-mpg on long highway travel, gentle rolling hills, @ 65-70, with AC 'ON.'
Thanks in advance for any additional data.
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Hey aerohead! Nice to meet you.
Let's see.
1) Whatever the frontal area is stock, my area is now -43 sq in that. -20 sq in per mirror, and -3 sq in from the antenna delete. (I heard a great quote from the lead developer on the Aptera. "We produce as much drag with the whole Aptera as the Ford F-150 does with both mirrors."
2) Empty, the weight is = stock-420 lbs. (That's the 66 mpg figure.) Laden it's stock+520 lbs (That's the 61 mpg figure.) I'm including myself in those figures already. That actually has a significant impact on rolling resistance.
3) Pirelli 4) P4 FOUR SEASONS PLUS - P185/65R15 88T
5) 44 psi, the max on the sidewall
6) Hmm... this alone may gank this particular approach. The self-coasting and engine idling the Toyota does accounts for a great deal of its fuel economy. To give some perspective, on my test route I go generally uphill first and then downhill on the way back. When I was testing v3.0, that barely moved between 40-45. But on the return trip how well and long it coasted made up the lion's share of the mpg, pushing it past 60 mpg. That's a +40% variance, which is primarily on "electric" and not the engine power.
In fact, there's a long, increasing slope on the way back and I get very fine data from precisely *where* along the slope the engine turns off, and then secondly when it starts the reverse blue arrow (i.e. regenerative power).
By the way, just FYI, my "testing methodology" is real world. I have the AC set to 72 F, the radio on (because I love music), lights on (if needed), wipers on (if needed), etc. So I get variance because of weather, et al. During testing I'm not too worries about it. I only consider real mpg to be a full tank of gas, i.e. driving in the real world for 500+ miles. That averages out conditions enough to make meaningful statements. But even then, there are confounds (like relative elevation of origination and destination points, etc.)
Hope this helps!