2008 Dodge 1500 QC SB 4x4 Hemi Auto 3.92 w/20's

My truck is 2 weeks old and now has 850 miles. I drive 75% highway and 25% light city. I run the cruise control at 65 mph. Mostly flat ground with a few rolling hills. Currently I am only getting 14 mpg for each of the 3 tanks of fuel so far. Light driving, no rabbit starts, driving easy. Also, the trans is constantly jumping in and out of gear, rpms bouncing between 1,700 and 2,100. This combined with the lousy mileage is driving me insane. Truck is rated for 17 mpg and the dealer salesman swears that it should get at least 17 mpg. Also, to change trucks means I would have to eat this one on a trade-in.

Any help or suggestions?

 

You have to let the motor break in, for the trans problem suggest that you take a tech from the dealer for a ride and show him what you mean.

 

I dunno man, I drive about 50/50 highway city have a somewhat heavy foot and have 650 miles on my truck now and on my second tank and got 16mpg. My first tank I drove like a bat out of hell and got 12. I'm figuring I might get it up a bit more. 4x4 hemi quad cab with trx4 17" aluminum wheels.

 

The heavy 20" wheels are gonna cost you a mpg or two, but you should still see 17 easy with mostly highway driving as long as you're not doing 80 mph. You also should avoid using cruise control and sustaining the same speed/rpms for break in period.
It will take a while to "break in" and see the mileage you will get over the long haul. Your tranny is probably just changing gears because with the terrain and the cruise at 65 you are probably right in between and it's downshifting on slight uphills and back downhill or on the flats. Again, not using cruise at that speed should help that situation.
Don't panic about the mpg's until you get past the 1st oil change at about 3000 miles, it still won't be getting the mileage it will when "seasoned" but should be doing significantly better than it is now.
I've got 35" tires, a lift, winch, and many other mods and weigh in at clost to 7000 lbs, don't have MDS on my '04 and still average 13.5 mpg around town and can hit 16 on trips if I keep it close to 70 mph...

 

Check out this thread for the RPMs (re: MDS)

https://dodgeforum.com/forum/3rd-gen-ram-tech/166379-rpm-hunting-with-the-cruise-on.html

As for mileage, are you going off of the computer or doing the math yourself? Some do not trust the computer at all and come up w/ completely different numbers by filling up, taking mileage, themselves.

Good luck.

-slide

 

In bold is part of the reason...unsprung weight and lower gears are killers of mpg.


The rpm jumping is the MDS engaging and disengaging....which it'll do a lot if the cruise is on. The puter uses way too much throttle too quickly so it always makes the MDS disengage. If you want the best mileage don't use cruise...

Use a slow and steady throttle to maintain speed on the highway/in the city...that way you'll stay in MDS and you'll notice the rpm's won't jump.

EDIT:The other guys beat me to it...so a lot of what I said is a repeat.

 

The "Idiot Box" says I am getting 15.5-16.5 mpg. Hand calc says 14.0-14.9 mpg.

 

Same truck here, at 1000 miles last week without exhaust mod I was getting 21.8 mpg on the highway with cruise set at 90km/h. Now at 1400 or so and new exhaust im getting 19-20mpg at same speeds, lost a little.

Only time im getting 14 is in a town and im on and off the gas, when im kickin it down im 8-11mpg

On avg id say im 17-18 so far

 

My idiot box has never said 13.0 mpg. But, Im on the road early in the morning and there are very few headlights on open roads.

-slide

 

Mine has

My overhead has always been pretty accurate...within 5% is pretty good IMO.