Originally Posted by Todd157k
2012 Laramie Longhorn 4x4 3.92, bone stock w/Bullydog. 20.3 mpg over a 167 mile trip, 72-75 mph (mostly on cruise control), 90% hwy (got off the fwy a couple times for some side trip stuff). There's about 1000 ft. overall elevation drop from me to SD.
My trip back was stuck in traffic almost the whole way (easter weekend) and my 20.3 dropped to 17.6 for the 334 trip.
My prior trips to SD without the BD, I was always 18-18.5.. usually the same speed.
Since I wrote the above (in another thread), I've made a couple more changes. I put a vararam intake on there and tested a few of the suggestions on here. My test run was to/from work which is 71 miles (r/t) consisting of uphill/downhill most of the way. In California, there aren't too many "flat" roads. Summing it up:
Stock = 18.5 avg
Stock w/ Bullydog = 20.6 mpg
Vararam w/ Bullydog = 19.5 mpg (ya, it got worse.. I'll explain below)
Vararam w/ Bullydog & MDS off (6th gear) = 21.7 mpg
Vararam w/ Bullydog, MDS off and running Premium fuel (91 oct) = 22.3 mpg!!!!
My mileage went down when I put the Vararam on there but for good reason. With a "Cold air Intake" it should suck in colder air. I modified my Vararam front to get as much cold air as possible. It worked.. but the IAT is now sensing colder air and richening up the mixture. Yes, that should be more power too, but at this point I'm looking for better mileage. Once I put the Premium gas in, and turning off MDS, the power gain took over the slight increase in mixture. I think the mileage went up with the MDS off is because the road is constantly going uphill/downhill so the truck never 'labors' to go up a hill and then kick-down a gear. I would bet that if it were flat roads, it would be better with MDS on.
If you do the math, an increase of 4 mpg will pay for the Bullydog and Vararam in about a year.