My 2009 Acadia does not shift out of gear when coasting (not on cruise control). The engine rpms stay high and sometimes even increase as the vehicle slows down. When I release the gas, it seems like the transmission stays engaged, thus the engine brakes, and slows the vehcle down. If I am driving say 45 mph and take my foot off the gas because I am heading towards a stop sign, the RPM's jump up, from maybe 700 to 1200, as if I had downshifted. This is not wanted, and it causes me to loose gas mileage.