Need opinions on trucks. Buying new (to me) sleeper truck 1998-2005. I am needing truck that has plenty of power but also need something that gets best mpg at 70 mph. What's your guys opinions?

 

Drive slower.

Depends on what you consider good mpg. We got 6.5 in a cfi t2000 with a c15 13sp running 65 to 70. Not sure what rear end ratio it had. The t600 setup the same got a little better. If you stay 2004 and older you can avoid the egr junk.

 

6.5 would be awesome. Im used 5.25-5.3 in one truck and 4.5 in other. The 4.5 mpg one we are working on because it should get better, I will know soon what it's doing now, my driver filling up soon. I replaced thermostats in it because were stuck wide open. Also was going to change air charge cooler before it went out last but they sent me incorrect cooler so sent out without swapping (has little leaks where cores/tank meet), it will be swapped Saturday morning before I send him back to Texas.

 

Everything is relative, and one person's mpg in their operation might be good, but it would be horrible in another operation. 6.5 average in my operation would cause me to pull out my .45 and shoot the truck and put it out of my misery. I won't settle for less than 7. But then, 70 mph is not my game. Fuel, tires, and maintenance running like that is too wasteful for my taste. I prefer to take more money home. I can bury the speedometer in my truck, but it will never happen.

But that is my operation. I wouldn't expect that if I was pulling logs or hogs. But for general freight, I wouldn't settle for less.

 

it really depends on a lot of things. where do you go? what kind of loads do you pull? i'd try to find a pre emissions detroit. that should do the job for you. a lot of people call me crazy.. the 14l detroits are hard to beat.. when they run right.

 

No truck gets its' best fuel mileage at 70 mph.

 

I would go with an engine with around 400-450 hp and 10 speed with 454 rears. That would give you at least 6 mpg+ have good pulling power. You could probably improve your mpg with something around 323, but might lose some of your pulling power.

 

4.54 sounds pretty slow for a highway tractor, my truck has a 4.64 and it runs almost 1700 rpm at 62 mph, my dads truck has a 4.33 rear end and I would still consider that a truck which only spends some time on the highway.