I am curious about what kind of mileage you guys get hauling your RV's.I get right around 14.1 hauling a 3,000 lb camper. Running around 60 mph. Usually over one mtn. pass and then the rest of the same tank used mostly on level highway.How 'bout you guys?T.I.A.

You don't have kids do you :-) Safety is another reason, going 20mph below the average speed is not safe, it's worth a few bucks in diesel to me.

Easier yet. Don't travel the interstates.

Easier yet. Don't travel the interstates.

Sometimes they are easier, sometimes they are not. There is somthing to be said for no stopping or slowing thru a town. Whenever you slow down at least one kid want's out. We do both, but I won't drive 55-60 in a 75 when the weather is good.

My truck is a lot happier at 70mph with the trailer than any slower and seems to get the same mileage as going slower. I think the engine is in a more suitable position at 2000RPM than at 1700RPM or something. Now we don't have any speed limits over 70 here and frankly I don't see the need to go faster. The last couple times I have been on the interstate I have just been drafting semis at 60mph (70mph speed limit). I stay far back so I wouldn't call it drafting but I figure he has a good reason to go slower and if I tail him then it's not solely my fault for going slow and then everyone passes us both at one time. Not like all these other stray cars going 10 under that everyone has to slam on their brakes for. I think everyone on a busy interstate should be doing the speed limit if they aren't in a semi truck. The ones doing the speed limit far outweigh the ones who aren't and a car doing 10 under is just a bottleneck in traffic. People get in the fast lane when they see a semi truck out of habit, not so with a car, so then everyone has their signal on waiting for everyone to get past so they can get over and pass the slow corvette.

On a 4 lane that isn't busy, do whatever you want. I did all those mileage tests years ago on a 4 lane that has 1 car every mile... I could do 45mph (65mph speed limit) and think nothing of it, people would get in the fast lane a mile back knowing they were gonna pass me since it was so obvious.

On a 2 lane, do the speed limit... Corners have their limits of course but if it's a straight road, do the speed limit! No reason to have 20 people behind you because some powerstroke in the 20th spot will try and pass everyone at once and create the biggest potential for a wreck ever. The only time I do this is on a 2 lane around here that has a long flat stretch that you can see a few miles on and has no driveways or anything. You give everyone else a second to pass and if nobody cares to make a move, that's when I make mine. I think its a given that the cummins dominates the highways so I like to give everyone else a chance since I will have no problem getting by everyone I stopped doing that a while back though, and its impossible to do with the jeep so I haven't passed anyone in a long time. Sit back and relax and enjoy the scenery. It's a mind game. You think going faster will make a difference, you must go faster to think you're not wasting time, but it makes little difference unless you're traveling several hundred miles.

With my truck a 2004.5 dually 4x4 auto towing our 9k bumper pull toy hauler I get between 9.5 and 11 at 65mph. We just completed a trip to Richfield Utah via West Yellowstone and back, and for the whole 4000 miles averaged 10 with many 6% grades. Our 2001 2500 4x4 auto averaged about the same at 60mph. I haven't figured out why why the 2004.5 gets the same at 65 the old one did at 60, or why the 2001 got 15-18 empty where the 2004.5 only gets 11-12 empty.

With my truck a 2004.5 dually 4x4 auto towing our 9k bumper pull toy hauler I get between 9.5 and 11 at 65mph. We just completed a trip to Richfield Utah via West Yellowstone and back, and for the whole 4000 miles averaged 10 with many 6% grades. Our 2001 2500 4x4 auto averaged about the same at 60mph. I haven't figured out why why the 2004.5 gets the same at 65 the old one did at 60, or why the 2001 got 15-18 empty where the 2004.5 only gets 11-12 empty.

Your 01 getting better mileage than your 04.5 can be explained with one word... EPA. Generally speaking, the older the truck, the better the fuel mileage (empty not towing) they got. The older the cummins the less the epa had their hands on them they were less restricted. But the newer the model the more emissions were added, timing retarded for NOX, etc etc. The up side is they do make more power than the older models and are more efficient at towing with 6 speed transmissions and better gear ratio options which is why you see better numbers towing.

Normally with my 28' fiver I get 14 mpg at 55, 12 mpg at 65, and 10 mpg at 70. With propane I get another 5 mpg across the board meaning 25.5 mpg at 65 mpg empty and 16+ mpg at 65 towing.

My 2001, auto,3.54 gets 13.5 towing 27ft Alpenlite with a gcw of 17,600 at 61mph. 61 or 62 is acceptable all over California. 63 can get you a ticket. Averaged 12.5 over 12,000 miles to Alaska, but Alaska has some hellish grades.