> The Bosch, Beru and NGK multi-electrode plugs have a service life of
> 20,000
> miles.  I don't know where you get 100,000 miles from, but here in
> Europe,
> no-one in their right mind would wait that long to replace their plugs.
>

I have iridium tip plugs in my daily driver Toyota Echo.
The first scheduled spark plug change recommended in the manual
is 196,000 Kilometers(about 120,000 miles).