So I just picked up a brand new 2007 Dodge Ram 1500 HEMI SLT Big Horn Edition.

The window sticker says 18mpg highway... I was set on cruise the whole way and only got 13mpg... what octane is required? or my other thought is that the engine is not broken in yet?

 

Remember those numnbers are estimates. Some Hemi's are lucky enough to see those numbers, others do not see anything and are just stuck with horrible hemi milage. What are the specs of your truck? 4x4?

 

4x4
3.92 axle ratio
limited slip rear diff.

I dont expect it to always be 18... but on cruise control going 70mph on a flat freeway, I would expect better than 13. Isnt MDS supposed to improvegas milage? not keep it the same as the old hemi...

 

I can never seem to get mds to kick in at any speed over 65. However, at 65 mph on cruise on flat ground I average over 20 mpg. I also have the superchips tuner too though, so I get 14+ at 85-90 mph with 87 octane on the 87 tune. with the performance tune at 93 octane, i get 14-16 at 65 mph. Hope this helps. My truck has 4500 miles

 

i think you gotta let it break in--mine was at 12-14 new and now that im at about 4500mi.
it has drastically increased to 17.5-18.5mpg using 87 octane only.
g/l

 

I assume you are watching the over head? If you want to see that number

1. Fill up your tank
2. Set the cruise at 60
3. Make sure your tires are inflated to the recommended PSI

You will then see your number.

 

I'm pretty sure the MDS is only rated for one mpg better than my '05 hemi qc without it.

The overhead has never been right for me.

I keep track with mileage, about 14.8 consistently. I have never seen 16 mpg. But on a long road trip my girlfriend drove for most of a tank of gas, on flat highway with no load while I slept and the average was 15.9 for that tank.

Most trucks are pigs. Heavy and square with big motors.

I am going to have to pull out the bull**** alarm for anyone who says they get 18mpg.

There was an article in consumer reports recently on how every window sticker mpg estimate is wrong. The estimate is based on some imaginary ideal situation. There was one super effecient car that was rated at 38mpg and really got 31 in the real world. I think it was a Toyota. The article was a good read.

 

I got 19.7 on a 140 mile trip averaging 70 MPH with the cruise set at 70 3/4 of the time. Call the BS card if you wan't but I've gotten similar numbers before. On a return trip from LA to Sacramento without any regard for speed and with a 600 lb ATV in the back I got 13 MPG.

 

I have got 18.1 on mine. but mine is broken in too. It was on flat ground, going 55 mph, with the cruise on. You also must realize that you are running "winter" gas right now too, which also give worse gas mileage. Just make sure you break it in right, and keep the oil and filter changed at the proper intervals and you'll see it. Having said this, I googles "winter blend gasoline" and came up with thishttp://http://www.theoildrum.com/sto.../13/234043/431
Maybe this help

 

Winter gas?