I have a '17 Cruze Diesel with the 6spd manual transmission, just shy of 10k miles. It has recently developed a very heavy shuddering/shaking/bucking behavior that comes and goes, usually under the following conditions:
-1700-2000rpm
-Fairly light throttle
-Speeds above 40mph (Gears 4-6)
When this happens, there appears to be a significant loss of engine power, and any additional throttle given worsens the shaking. Not much noise to speak of. If anything, it sounds faintly like the engine is sputtering. Reminiscent of EGR issues in my old Honda Insight.
Shaking immediately stops when clutch is pressed in and transmission shifted into neutral. Engine sounds fine and revs normally in neutral while coasting at these speeds, but any attempt to shift back into gear and drive results in more shaking. I have to coast/brake down to a lower speed, shift into a lower gear, and then pick back up to speed in order to continue driving.
Other users have mentioned premature failure of the flywheel as well as injector issues