i run platnum 4's in my jeep and i like them i also refuse to use champion plugs in anything just like the gm tech. the 4's did increase mileage a bit and did improve economey but they also wore out at about 15k. i myself really like ngk plugs for just about everything but have not tried them in the jeep yet. another thing i suggest doing is replacing the coil strip when you do the plugs. they are suppoused to only last about 70k and range from $80 (advance) to $120 (mopar from internet) good luck