i always figured that if any of this stuff actually worked it would be OEM. CAFE standards are tough and mileage bragging rights are always on the minds of the marketing people. if a simple spark plug change could really make a positive difference in MPG, you can bet they would be in new cars. even at $10 more per plug that's only $40-$60 on most cars and thats a drop in the bucket on a $20K-$30K ride...
