I've tried the Autolites, the 2.2 did not like them, the counter guy gav me a deal on Bosch with 4 ground electrodes , 2.2 said no thanks , I purchased Dellco Iridiums, very happy little 2.2. I did notice throttle lag hard start in hot and cold weather, I put the Autolites in a week before trip to Florida in Feb, went from minus 3 F to plus 98 F in a matter of 48 hours, so I did have lower MPG by about 3 to 5 MPG, and that proved to me go with the AC Delcos

 

I am not sure what it is but many engines today need to keep with the same plugs as they came with. Too often they just do not run well with changes. Some other plugs will work but many will not.

I have seen this first hand on a Honda Civic. It had NGK and then got a fresh set of Champion. It ran for crap. My buddy to it to a import mechanic and he said It just needed a set of NGK plugs. He changed them and touched nothing else and ran fine.

As for all these promises of E3. Split fire and 4 grounds they are all jokes as electricity goes the path of least resistance. You are not going to add HP or MPG unless you really had something wrong with the old plugs. Splitfire had to stop promising more HP as the government called them on it.

You can get better plugs by going platinum etc. as they will wear slower and last longer.
There is no great secret here just plugs that are designed to last longer and not break down creating more resistance.

Most GM cars use Delco and some Bosch.

 

Well when i had my 69 chevelle with a 540 big block custom race motor which was chevy gen 2 block motor ,i ran autolite plugs and index them a race term my motor ran like a raped ape for example ,but that is apples to oranges .. The 2.2 runs the best on the delco hands down plus you can get at least 90,000 on them so less maintenance on your part but lucky i did not try to gap thank god and i know the reason why..