Scotty addresses “special” spark plugs (like E3) at 3:49 in video.  In short, they don’t improve performance or mpg.  Just stick to the OEM spark plugs.

https://m.youtube.com/watch?v=eMc9RoTw90I&feature=emb_title

E3 spark plugs are just so much snake oil.  Use the manufacturer's recommended brand and heat range plug.  Razmig has it exactly right.

That's because spark plugs do not offer any sort of "extra" performance. Sure, if you use the recommended spark plug type, you'll maximize the performance of your engine (allows the engine to make the specified horsepower output), but it's just not possible for a spark plug to boost performance (exceed the specified horsepower output, unless you are running a performance tune which requires a new spark plug gap). It's all psychological...when you change your spark plugs after 80k miles, you definitely will feel a boost in performance because you just replaced your worn out spark plugs with brand new ones. The older the spark plug gets, the less of a spark it can produce because the gap between the electrode and ground get wider, which won't allow your engine to make maximum power. The spark plug creates a spark from the high voltage produced by the ignition coil, so really the ignition coil is responsible for whether the spark plug fires more powerfully.

Same goes for the multi-ground spark plugs...it doesn't increase performance. The multi-ground is used for even electrode wear for higher voltage applications. So if your manual specifies to use multi-ground spark plugs, then downgrading to a single-ground spark plug will decrease your performance since the higher voltage system will wear them out faster and unevenly. But if you upgrade to a multi-ground spark plug when it's not required, then you won't notice any difference at all.

In short, this is why you don't notice a difference between the two spark plug types, they're making the same spark essentially.