On several occasions, I have noticed the 1.6T engine will significantly ping (a rattling-tin-can-like sound coming from the engine).
This condition is reproducible and ONLY occurs when the vehicle has been driven for a significant amount of time on a long distance trip (say, 50 mi or more) where the engine is allowed to reach normal operating temperature AND the vehicle is subsequently shut off for a short period of 10-30 minutes (about the time for a typical store visit). After restarting the vehicle and beginning to drive after that short period is when the noticeable pinging begins (I'll call this the "second drive").
It's as if a sensor or computer module is misinterpreting engine conditions during that "second drive" described above and not calculating the correct air/fuel mixture. When the pinging is experienced, it is quite noticeable and I have tried different drive modes and increasing the RPMs using the paddle shifters with no improvement. I have also tried pulling over and restarting the vehicle, and again with the same pinging outcome. Of course in EV mode, this condition doesn't apply.
If the Tucson Hybrid is allowed to completely cool down, it drives normally again (no engine pinging).
After some research, others describe having had the same experience with the 1.6 Turbo engine as far back as 2012. The vehicle is not throwing any codes based on my scan tool, but it's possible the vehicle is too new for my scanner.
If anyone else notices a similar condition on the Tucson Hybrid, please report here. My concern taking this to a dealership at this point is that it's challenging for a service center to reproduce because of the time it takes, and, I don't want to hear, "we couldn't reproduce the scenario". If enough others are experiencing the same, it demonstrates a systematic problem. Otherwise, it could be an isolated problem on my vehicle that just needs to be addressed.