Shudder in, Subaru forester 2017, since it was purchased. Car has 2.5 non turbo engine with only 1000 km on it. Shudder appears to occur most of the time between 40-60 km, WHEN off the throttle then back on. Shudder on times also occurs at high speeds again a shudder or "miss", disappears when heavy throttled.
Go back to the dealer and tell them to fix it or give you a different one that works.
This could be many things but if it's that new and already having problems then I would get it swapped for a different one.
The problem itself could be many things and to find out we would need a computer readout with all the engine management sensors and what they are doing during the shudder.
The only easy thing I can think of is its a loose spark plug wire but it would shudder everywhere if this was the case.