In the past decade or so, automakers have turned to downsized turbocharged engines—often with direct injection and higher compression ratios—to boost efficiency. These fancier power plants tend to require fancier iridium spark plugs, the higher cost of which creates a big incentive for fakes.

 

Torque Test Channel took a $500 batch of iridium plugs from NGK, Champion, and Denso bought from Rock Auto, Amazon, and eBay, and found that about one third were fakes. That means unsuspecting buyers are likely to be wasting money (the NGK plugs retail for $70-$80 for a set of four) on parts that won’t last as long as they are supposed to, and could hurt performance and gas mileage.