How much can a bad serpentine belt affect MPG?

It was not set properly in the grooves when changed a few months ago but changed again last weekend. How much of a difference is it apt to make?How much can a bad serpentine belt affect MPG?
None. Just will get longer life out of the new one.How much can a bad serpentine belt affect MPG?
Not at all it will just break and leave you stuck on the side of the roadHow much can a bad serpentine belt affect MPG?
it don,have any thing to do with the gas mileage, just the electrical part of the car.

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