Modern automatics are smart enough to downshift when coasting down a steep hill. I've driven a Duramax with the Allison up and down mountains. Absolutely amazin

Modern automatics are smart enough to downshift when coasting down a steep hill. I've driven a Duramax with the Allison up and down mountains. Absolutely amazing. You just slightly touch the brake pedal, and it downshifts and the exhaust brake enables.