Before I bought my new truck I was led to believe the new 24 valve got better fuel milage. Both my new truck and old truck are set up the same; 3:54's , diesel , extend-a-cab , auto , etc. Old truck got between 750- 850 km's per tank and the new one is lucky to see 650. Anyone else seen a huge difference between the 12 and 24 valve motors? The new one even with the HP increase over the 12 valve doesn't seem to tow as well either.