Quote:
Originally Posted by Cd
Jim, I tried to input some of your data into the aero and rolling resistance tool https://ecomodder.com/forum/tool-aer...resistance.php
However, I don't know some of the variables, such as your final weight and such.
When you have a moment, can you input some of the data to get a rough estimate of the final cD ?
BTW, If i understand correctly, a tail like this would only show an increase of 4.3 MPG on a car like mine that got 42 MPG at that same speed you traveled.
( And likely much less, since each cars body shape is different )
I'm a bit confused when you all say you are getting over 80 -90 mpg when traveling at 56 mph.
Stock, your car got around 55 -60 mpg at that speed, correct ?
Is the 80 -90 -100+ mpg using tricks, like coasting, or coasting with the engine turned off ? |
Hi Cd,
********* Topic 1 - MPG **********
I'm going to respond to your question about the Insight's typical mpg first. When Darin had his Insight, he generated the following data.
Notice at 56 mph, he is getting 89 mpg. This is the typical gas consumption at a steady speed with no special "tricks" going on at the time. When we talk about getting over 100 mpg, then typically the "tricks" are involved while driving at the same speed.
********* Topic 2 - Fuel Usage **********
The statement "BTW, If i understand correctly, a tail like this would only show an increase of 4.3 MPG..." can be elaborated.
Your typical MPG is stated as 42 Miles/Gallon. Let's switch units to Gallons/100 Miles.
42 Miles / 1.0 Gal = 1/42 Gal/Mile * 100 = 2.38 Gal/100Mile
The Insight gets typically 90 mpg, or 1.11 Gal/100Mile
So if I build a tail that increases mpg by 10% to 90*1.1 = 99, then consumption is 1.01 Gal/100Mile.
If you build a tail and get 10% better mileage, then your consumption is 42 * 1.1 = 46.2 mpg or 2.16 Gal/100Mile.
Now let's compare our fuel consumptions with tails:
--------MPG Gal/100Mile Change (Gal/100Mile)
Insight-99.0----1.01--------0.10
Cd -----46.2----2.16--------0.22
Notice how your tail helps to reduce gas consumption much better than the same with the Insight.
********* Topic 3 - Insight Cd **********
I looked at the Cd generator and see that there quite a few assumptions about input parameters. It makes me leery of trying to fill out those boxes. However I can say that adding the tail raised the typical body weight of the car by 40 pounds or so. I still had the IMA battery installed.
If you have further questions about filling these boxes please let me know.
Jim.