The chatter on this here, and my own experience with my 91
Civic, is that the plugs that the car's owner's manual says
to use are best for gas mileage and the car. Longer-life
versions don't affect gas mileage.

Anecdotal reports have not been favorable to Bosch.

"Rob" <rdbdriver@blomand.net> wrote
> I've got a 2002 Civic LX 5sp and am getting great gas
mileage, but it's
> time to change out the plugs at 110k, so checked at the
auto parts store and
> they must of had a dozen choices that would replace my
stock plugs.
> I understand my stock plugs are the long life Iridium
plugs that cost
> 12.75 to replace each which I have no problem putting back
in , but was
> wondering if any body has experience with some other
choices like the Bosch
> Platinum's, Denso or some of the other NGK choices.
> Did your MPG increase, stay the same or get worse. I
mostly looking for
> a plug that might increase my mileage, the long life plugs
are nice to have
> , but changing plugs out on my Civic is so easy and think
it's a good way to
> check the health of my high mileage Civic ever so often.
Thanks for any
> advice.
>
>