Wrres

The grade control is not the engine brake on gm's with the duramax. Grade control is for when you are off road creeping along under 10 MPH with a 2-ton camper in the bed. It holds your speed steady on down slopes and uses both the brakes and engine brake to keep you creeping. It is a marvelous thing if you hunt and camp in the mountains as I have done with various camper's over the last 40+ years. And the engine brake is also a marvelous thing when driving said camper on mountain highways. I rarely ever have to use my regular mechanical brakes.

How much weight can it carry in the bed, such as a truck camper? Or a load of rocks?

They just sent me a great (not) $20 off to update for only $139 for Christmas. This is just simply stupid expensive. I bought a top of the line Garmin for that price and I get map updates 4X per year FOR FREE along with free traffic!!!! And the Garmin does a ton more than the Chevy nav. I am OFFENDED at the price they want for this!