Can spark plugs improve fuel efficiency?

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Mon 24 Jul 2006 12:33
Can spark plugs improve fuel efficiency? - y2k+4
Interestingly, despite the recent swathe of problems arriving from my dear Ford Focus, it has managed to come up with 40mpg and 42mpg on it's last 2 tankfuls. This is substantially higher than what it has been achieving pre-service (35mpg, average). Apart from standard fluid changes (coolant/oil etc - which have never affected fuel efficiency before) the only thing replaced were spark plugs. I kept the oil topped up anyway, so I was wondering if this reduced drinking habit could really have come from something as cheap to replace as spark plugs?
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Mon 24 Jul 2006 12:55
Can spark plugs improve fuel efficiency? - robcars
I would imagine air filter and fuel filters may have helped a little?

new spark plugs may make a difference but if they made that much difference then I would have thought they would have been misfiring (and causing other problems for you)
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Mon 24 Jul 2006 12:59
Can spark plugs improve fuel efficiency? - bell boy
i always find they run better with them removed to be honest......
#

ok i lie they are the most important part of the ignition system its like putting wellies on with holes in them
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Mon 24 Jul 2006 20:43
Can spark plugs improve fuel efficiency? - Lud
The gap widens as a result of the electrodes burning away. With deterioration in the plug's insulation as well, fuel consumption can get worse, along with performance.

I too would think the air filter, if it was replaced, might have made a difference. And isn't it possible (not likely I agree) that some fine tuning of the car's electronics, injection pressures and so on might have been done? It is probably supposed to be.
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