I tow our C-Dory 25 with a 2003 Chevrolet Supercab 2500HD with a 6.0 L v-8 gas with a 410 rear end. I average a little better than 9 mpg when towing. It does OK on the hills, but I do slow down some. We towed the boat from Bellingham to Phoenix when we purchased it. Other long trips include...