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'06 Forester gas mileage experiment

('06-'08) 
784 views 4 replies 2 participants last post by  DragonSubie7 
@Danspan -

Watch out for expectation bias...
Similar to the placebo effect, if you replace a part that you think will improve performance, you may observe improvement that is more a result of what you expect than an actual difference. Your comments like "seem to start quicker" and "smoother" are hard to quantify, but easy to imagine.

If a car has a problem that's corrected, there will likely be a difference that could be measured.
If you make a change that you think will improve mileage, your mileage may improve, but very minor changes in how you drive can dwarf any effects of changes from one functional component to another.

The point is that you can easily fool yourself into believing that something you did made a difference, where the actual difference is you.
It's all part of being a human, and there is a reason that sugar pills can cure an illness.... and they do.
In many medical studies, a sugar pill can improve the condition of 20% of the people who think they are given a new and effective drug.
It's the belief and what follows is self fulfilling prophesy.
 
@Danspan -
I began my note with "Watch out for expectation bias... "
My point was that as a part of human nature, humans are by nature susceptible to it.
I never said you were "unduly vulnerable", as I don't know that and did not intend that, but it would be equally untrue for you to say you are immune to it.

It's great that you want to find out ways of getting better mileage... but consider this...
Auto manufacturers are desperate in their attempt to improve mileage in their fleets to meet government mandates.
If all it took was some different spark plugs, or any other commonly available accessory, why wouldn't they use them...
It's a rhetorical question.

What you may find are wear items that have affected your particular car's performance, and that might be improved by replacement.
Adding air to your tires when they are underinflated can make a huge difference. So does the weight you transport.
So does the number of stops you make, the traffic you do, or don't, encounter, the ambient temperature, the BTU's in your fuel blend, the wind velocity and direction, etc, etc, etc, etc...

In order to assign a result as to cause with your experiment, there are a lot of variables you cannot easily (and in many cases cannot at all) control.
MPG is a result. It is a measurable end product of all those input factors and by that is entirely dependent on them, which will make it difficult, if not impossible, to assign any particular value to a change you make, especially as you add changes as time goes on.


That being said, good luck.

In my case, I notice a dramatic improvement in mpg's just by slowing down.
 
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