When driving our 2017 nissan leaf electric vehicle at about 65 mph up a steep hill / steep incline, we are experiencing a loud clunk from the battery area when the vehicle climbs over 2000ft elevation within a short distance (16 miles). the clunk always happens within the same 1 mile stretch of road and happens every time we drive the car from salt lake city, ut (4,226 feet) to summit park, ut (6,887 feet). we first noticed it this summer 2019. there is an audible clunk and it can be felt through the passenger foot-well behind the driver's seat. there is a thread on the mynissanleaf.com discussion forum that describes the same issue (http://www.mynissanleaf.com/viewtopic.php?f=30&t=19883&p=565545#p565545). the contributors think it has something to do with the electric battery case expanding or contracting under pressure. i'm planning on letting the nissan dealership know and pointing them to the discussion forum (the discussion information is here: http://www.mynissanleaf.com/viewtopic.php?f=30&t=19883&p=565545#p565545)