Quote:
Originally Posted by MetroMPG
Cue the analysis of Eibach's testing methodology (and credit to the company for posting the details on their site):
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Sure, I'll bite.
At 70mph, such a draggy car spends 83% of its power overcoming drag, so highway FE is a pretty good drop-in for Cd. Essentially, they're reporting having reduced the Cd from 0.37 to 0.31 by dropping the suspension an inch. Not likely, but who knows without a valid test?
Their methodology isn't the worst I've ever seen. They did lots of things right: the test was long enough to burn 6.4gal on one run and 7.2gal on the other. That will eliminate transient effects like cold starting.
Unlike at our fuel economy runs, 0.1gal of fueling error wouldn't have changed the outcome much. Good of them to test at 05:00 on a Saturday when traffic wouldn't interfere, and good of them to make sure the temperature was the same.
Now for the bad: Why did they wait six weeks between the "before" and "after" runs? What else happened to the car, the road, etc, in the mean time? When you wait six weeks between runs, you need to do A-B-A for sure.
Their sample size, n=1, is terrible science. If they don't try to do a few identical runs, they won't know how good their methodology is.
Just because an independent company helped in the testing, does not make it double-blind.
The article itself is awful. This advertorial is just a usual piece of sponsored "reasearch", unfit to be published without the disclaimer "Advertisement". Note the article ends with information about price, applications, and how to order Eibach lowering kits.
Article: worthless
Testing: looks clean, but without independent verification and higher sample size, it's worse than worthless.