Just thought I would share as well.
1.4T with a 6 speed manual in a 2012 LTZ. Always thought something was not right about the transmission. If shifted a tad to quickly, it would grind.... particularly at 1-2nd sometimes 2-3rd. Told the dealer and they simply would dismiss it. It was doing that from day 1. I've been driving a manual since I was 16 but I simply adjusted for the Sonic.
At around 78k, I started to hear a transmission whine at all gears. It got progressively worse. Dealer agreed to replace the transmission under warranty. I paid extra to go ahead and replace clutch/flywheel while they had it out. Cost for the clutch/flywheel was around $900 with the transmission estimation at $4k (but not charged because of warranty).
The car feels great right now. No grinding even if I shift aggressively.
Still like the car. Great commuter with a bit of fun tossed in. However, it has been in a shop more times than I like.... with the exception of the clutch/flywheel, brakes, and tires, everything has been covered either by warranty or extended warranty. Still mixed feelings about what to do when my warranty runs out at 100k.
