IMO, I’m not surprised that the tow-haul makes a pretty good performance mode. I’m guessing that the ‘standard’ shift program is optimized for gas mileage, and like the 1-4 skip shifter on the Vette, and uselessly tall 6th gears on a variety of performance cars, this is one more technical trick that lets automakers get better CAFE numbers and still provide useful and fun vehicles!

https://www.chevyavalanchefanclub.com/cafcna/index.php?threads/tow-haul-button.8761/