I regularly tow a 17ft bass boat around to inland michigan lakes. Normally I can expect between 10 and 14 mpg when the boat is hooked up. I pull with tow haul mode on. Over the past week I have been putting tow haul on and setting the gear select up to 8 so the hemi will not go into 4cyl mode. Watching the mileage I've been getting about 16.3 like that. The lakes I'm going to are the same as always , same gas, same driver lol. Any ideas as to why the mileage would be better?