I'm looking at a stunning 2001 K2500 with 6 L engine. The current owner claims ~11mpg towing a small bass boat. What can I expect with a light foot at 65mph and no towing? Does anybody know if the 6L K2500 is significantly worse than the 5.3L k1500? I'm now driving a '96 5.7l K1550 and routinely squeeze 17-18 mpg out of it on the highway and never get worse than 15-16. Thanks!