Coil on plug has a magnetic core, all ignition coils have one, its size and permeability determine the maximum amount of flux density it can hold just like a sponge can only hold so much water. Increasing the magnetizing force with more coil turns or current does not increase the flux, just helps to burn it up.
To store more energy need a larger core, space requirements or a core material of a greater permeability, more expensive, have bean counters to deal with.
The energy stored in the the core is measured in joules and is the product of voltage, current, and time, time is somewhat fixed, how long it takes that magnetic field to collapse, normally a fraction of a microsecond.
With a larger spark plug gap, it takes a much greater voltage to ionize the air fuel mixture, and since the energy is finite, the current goes down. Higher voltages with weak current are more subject to blow out by the turbulence in the combustion chamber. To put this as basically as possible, specifying greater gaps is tantamount to being without technical knowledge or insane.
There are consequences, with blowout, the fuel is not ignited in the combustion chamber reducing both performance and economy but is burnt in the catalytic converter causing it to fuse and restrict exhaust flow further decreasing economy and performance plus disastrous to your wallet.
Back in the mid 80's, our EPA told us to get rid of the variables like ignition timing by rotating the distributor, could never to this correctly, so goodbye distributor, out came the distributorless ignition system using crank and cam angle sensors. This required a coil per plug, but also had to deal with bean counters. so one coil had to fire two plugs, the one igniting, the other 360 crankshaft degrees apart. Very poor, don't blame engineers, either do it their way or will find somebody else.
Voltage had to be doubled, that halve the current, both had a weak spark and misfires, finally had to give up and use a coil per plug. Your Elantra has this.
Spark plug really has not changed much in the last hundred years, ceramics go back thousands of years, platinum and iridium is better doesn't get eaten away as quick as copper does by that spark. But still have that center electrode insulator and still burning carbon that builds up shunting that already weak spark back to ground.
Using top grade fuel and Seafoam to kind of clean up that carbon, still only good for about 15K miles, pull them and use my walnut shell spark plug cleaner to see that center insulator nice and white, do this one more time at 30K, at 45K replace them. One and a half drive around the earth is enough.
With summer gas holding at 65 mph, getting 50+ mpg, at 75 so I don't get rear ended, drops to 46, by manually shifting around town, crazy AT will shift into 5th gear at 25 mph, some idiots think this saves fuel, really puts a heavy load on the engine, get more like 35 mpg.
Don't even bring up this stupid winter gas, energy level is about 25% less, EPA insists on this, because it takes about a minute longer for the engine to warm up. They learned around in 1998 their engine emission control devices are worthless until the engine reached operating temperatures.
Put a heater in the O2 sensor, wanted this in the cat as well, these small engines don't have enough power to heat up a cat in a few short seconds. Was totally impractical, so went to the oil companies to add oxygen to the gas.
Still do not do emission testing on a cold engine, may learn oxygen enriched gas is also worthless, but this is the EPA. Yes, I could tell them this to their face. Ha, call themselves green, correct word, green out of your pocket.
