With 1/4 tank of gas, the car started bucking and losing power as if there was no gas at all. Pulled over to side of highway on an exit ramp and let it sit. Car would not restart or would run only for a couple of seconds. There was no check engine light. Car had been burning a lot of oil in the months prior to the event, most recently a quart every 700+ miles. There were no oil leaks observed nor any smell, so it was being burned somehow. The oil level at this event was between the two dipstick marks.

I had car towed to a nearby garage who eventually did some diagnostic work and was focusing on one of the middle cylinders not firing. Spark plugs were all clogged up. Direct injectors were functioning normally, and fuel system was okay. So I ad car towed to a more local garage who concurred with the first one's diagnosis and further determined that that there was no compression in suspected cylinder; however there was no carbon build-up in the valve head area. Valve cover gasket was leaking.

The month before, I had been mailed the Theta engine lawsuit settlement notice which simply said that the 2017 Sonata was part of the extended short block warranty and did not specifically exclude the Gamma engine. However, since my engine is a Gamma II engine then it was denied when I tried to register a claim. It is the opinion of the 2nd garage that there is probably connecting rod failure. Had car towed to Hyundai dealer who (after a week) has yet to provide me with a diagnosis. I filed a complaint with Hyundai's case management department and after a week of pestering them, the case manager "Judith" has yet to call me back. If my Sonata has a different engine then I never should have been mailed the Theta settlement notice in the first place. Since then, I have had to rent cars for my work and have over $1K in diagnostic charges with no end in sight. Hyundai needs to make this right and don't intend to let them get away with this. I have owned many cars over the years including other Hyundai's, many over 100K miles, and none have ever had major engine issues like this.

Update from Dec 22, 2021: 12/22/21 - Hyundai of Lancaster (PA) has, at the request of my Hyundai America case manager, requested "Assistance" from Hyundai America, meaning that they're asking the corporation for permission to replace or repair the engine without cost to me. If granted, and I'm not holding my breath, I would also be reimbursed for car rentals as well. In the meantime in a couple of weeks I'm going to have it towed to a trustworthy local garage to have it evaluated for engine repair.