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Istas · 06-08-2009, 05:50 PM

Aerohead: Thanks for bringing that to my attention.

You're using this calculator, here? Aerodynamic & rolling resistance, power & MPG calculator - EcoModder.com

I put my car's Cd (0.33) and weight (2830, plus 200 pounds for the driver) in there, along with the original area (20.63 sq ft), as well as the rolling resistance measurement I got last week (0.0103, I'll be re-doing this to check), then dropped the engine efficiency to .21 to bring the numbers more in line with my experienced fuel mileage. (derived by fill-the-tank-and-calculate, but better than nothing)

Using that as a baseline, it spits out 35.96 mpg at 60mph (my preferred compromise highway speed). When I drop the area to 20.13 (which is what it is after passenger mirror removal and driver mirror fold-in), and plug in a Cd of 0.23, the calculator spits out a fuel economy of 45.71 mpg at 60 mph.

I know all of these numbers are very rough, but a Cd of 0.23 is a lot less intimidating than 0.11, heh heh.

I've also taken the air conditioner belt off, and will, when next I need tires, be switching from 185cm-wide 44psi-max tires to 175cm-wide 51psi-max tires.

I'm likely going to pick up some airtabs and see how that helps the airflow down and over the rear window and trunk.

I've also pondered just riveting a flat sheet-metal spoiler onto the back of the trunk, to help airflow separation.

That Merkur looks interesting, I think if I was going to try that route I might just opt for a full Kammback instead. Which I might do, but that would be a daunting task for me at this point.

06-08-2009, 05:50 PM	#18 (permalink)
Istas is not covered in bees. Join Date: May 2009 Location: Seeley Lake, Montana, USA Posts: 207 Honda - '05 Honda Accord EX 90 day: 27.16 mpg (US) Insight - '00 Honda Insight w A/C 90 day: 66.55 mpg (US) Thanks: 53 Thanked 51 Times in 26 Posts	Aerohead: Thanks for bringing that to my attention. You're using this calculator, here? Aerodynamic & rolling resistance, power & MPG calculator - EcoModder.com I put my car's Cd (0.33) and weight (2830, plus 200 pounds for the driver) in there, along with the original area (20.63 sq ft), as well as the rolling resistance measurement I got last week (0.0103, I'll be re-doing this to check), then dropped the engine efficiency to .21 to bring the numbers more in line with my experienced fuel mileage. (derived by fill-the-tank-and-calculate, but better than nothing) Using that as a baseline, it spits out 35.96 mpg at 60mph (my preferred compromise highway speed). When I drop the area to 20.13 (which is what it is after passenger mirror removal and driver mirror fold-in), and plug in a Cd of 0.23, the calculator spits out a fuel economy of 45.71 mpg at 60 mph. I know all of these numbers are very rough, but a Cd of 0.23 is a lot less intimidating than 0.11, heh heh. I've also taken the air conditioner belt off, and will, when next I need tires, be switching from 185cm-wide 44psi-max tires to 175cm-wide 51psi-max tires. I'm likely going to pick up some airtabs and see how that helps the airflow down and over the rear window and trunk. I've also pondered just riveting a flat sheet-metal spoiler onto the back of the trunk, to help airflow separation. That Merkur looks interesting, I think if I was going to try that route I might just opt for a full Kammback instead. Which I might do, but that would be a daunting task for me at this point.