Just traded my 2019 1794 4x4 in on a 2021 GMC AT4 with 3.0 duramax....the mileage is incredible, so far I havent had any issues with the GMC with about 2k miles, the tundra had zero issues biut was just old and dated and I was avg about 12-13 MPG on highway.....I know the tundra will last 200k+ miles just hoping I can get half that with the AT4.....The AT4 rides smooth and is a joy to drive