You're really trying to start a fight here aren't you?

I don't know what spark plugs came stock in the VX (some other member might know & chime in).

As far as the best replacement ... That'll depend on everyone's preferences. There are too many variables for any one company to honestly lay claim to providing the best fuel economy. To be honest with you, I don't think that the spark plug will really have a significant impact on gas mileage (let the bashing begin).

When replacing spark plugs, I'm more concerned with longevity rather than economy. I'm only saying that because I can't really 'feel' a difference when running better or cheaper plugs, but some definitely last longer than others.