2015 grand cherokee diesel 4x4

looking into getting a used gc with 74k miles on it. during the test drive at highway speeds, the steering wheel was moderately shaking. not like a death wobble, but enough that i was hesitant on buying it then. is this normal for gc’s? also, anybody with these diesels have any long term feedback on it? problems, mpg, repairs, etc? thank you in advance