The vehicle consistently exhibits a shudder (vibration, tremor) when (1) the vehicle is warmed (driven at least 10 miles from cold start), (2) moving at a speed above approximately 30 MPH, and (3) the throttle pedal is depressed. Usually, but not consistently, the shudder immediately dissipates when pressure to the throttle pedal is released or when the transmission is put into neutral while the vehicle is moving. Additionally, when the vehicle is driven into and in a right hand curve, the shudder is NOT present regardless of any or no pressure on the throttle pedal. In a left hand curve, however, the shudder is present often without any throttle pressure. When coasting on a straightaway the vehicle typically, but not consistently, exhibits no vibration. Road grade does not appear to have any impact on the issue.

All observations of shudder have been with ambient air temperatures from 35 to 77 degrees, altitudes between 6000 and 10,000 feet above MSL, and the transmission in the normal/standard mode. The shudder is felt most acutely in the center console. The problem can be observed most visibly by a lateral (side-to-side) shudder of the center console armrest when it is in the fully raised position. I guesstimate the shudder frequency to be 5 to 15 hertz, but have not observed if it might change with higher speeds as I am limiting speed per the new car break in procedure.

Dealer did attempt to find problem source, but was unsuccessful. Dealer test drove two other 2015 Q70s (AWD 3.7) and observed same problem. Dealer requested Infiniti engineering support. They will arrive on 17 June to further investigate.

I have requested Infiniti to repurchase vehicle under the Colorado Lemon Law. I'll see how it goes. Odd that issue has not been reported by other owners.