Quote:
Originally Posted by Xist
Aerodynamic modifications:
Both side mirrors?
Grill block
Air dam
Belly pan
Wheel covers
Wheel Skirts
Six users posted results for deleting side mirrors, average: 2.58 x 2 = 5.08%
Grill blocks averaging 2.79%
The average air dam listed at yielded a 3.775% improvement.
Belly pan: 3.48%
Wheel covers: 3.16%
Rear skirts: 2.88%
I do not know if air dams and belly pans yield as great an improvement together as used separately, as well as wheel covers and rear skirts.
Two of the rear skirts were on trucks and both commented that they covered a much larger gap than on a passenger car.
However, multiplying those six modifications suggests a 23.1% improvement.
When you removed the seats, upholstery, air conditioning, and power steering, you stated that you removed 115 pounds from a car that you previously wrote was 2300 lbs: 5%.
Didn't you say that you already reduced the weight by two hundred pounds? That would total 12.6% less mass.
The rule of thumb given on here is that for every 2% improvement in aerodynamics or mass, you increase your fuel economy by one percent, so between those two, in theory you increased your fuel economy 18.6%, taking you from 25 to 29.6 MPG. The wiki suggests that increasing tire pressure is good for another percent.
Didn't you also cover your windshield wipers and install side skirts? One user reported 1.5% and 1% respectively for those.
I see 30.69 MPG.
Indeed!
I did not see all of your modifications in your garage. It currently says that you have Mazda tires. Didn't you replace those with spares? What do you have now?
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Xist! I haven't forgotten about you, just had a rather rough evening yesterday. As I was looking over your post, I found some discrepancies that need to be addressed.
I have lowered my Cd by 18.485% (0.33 down to 0.269, last tested in May 2015), which should in turn give me a 9.24% increase in mpg. This is a far cry from the 23.1% you suggested! It makes me wonder if Ford "fudged" the Cd numbers to be better than they reported?
You got my weight wrong
the starting weight is 2478 pounds for an auto ZX2. 2300 is the weight I want to attain when
I am in the car driving, so I want the car to weigh 2125 pounds by itself. My 115 pound weight reduction would equate to a 4.64% drop in overall weight.
I have taken the wiper cover off and the side skirts till I can make better versions. So we have to lose those 2.5%
Over all, it looks like a 11.56% increase in fuel economy, or from 25 mpg to 27.89 mpg. Adding in the extra percentage for tire pressure brings this number up to a measly 28.14 mpg!
So how is the results much better than the math? We have the wrong starting point! I came to Ecomodder averaging nearly 35 mpg/40% over EPA! So we must use this as our starting point.
Now using the 11.56%/18.6%, the math says that I should have gone from 35 mpg to 39.046/41.51 respectively. This is interesting as it nearly perfectly matches my 2nd and 3rd tanks. I did not have hardly any mods at this time though, other than a partial grill block, lawn edging air dam, increased tire pressure and the ScanGauge.
Adjust the nut FTW!
My full mod list can be found
here. I did switch to 14x4 space saver wheels earlier this year. They were quite heavy compared to the Mazda MX3 wheels (17 vs. 12) and they increased my rolling resistance, so I switched back to the MX3 wheels with coroplast covers. They are working beautifully, I just need to wrap them with some RE92s and it will be perfect then
