Second tank, 70% highway, 30% city my figures 17.7. How does this compare?

 

Sounds good, you've got a lot of breaking-in to go. It took about 2000 miles before I began to see the biggest change in mileage.

Over 13,000 miles now 20.4 mpg on Interstate traveling 70-75, except for fuel stops and privey. ( Computer read 19.6 mpg, always reads lower than calculated mileage.)

Around town up and down these hills, 18.6 mpg, not bad for 4.10 axle, of course stick tranny helps.

 

Still on my first tank (that I filled) only about 500 miles total and about a 60/40 mix of city/highway. Computer shows 16.7 to 17.3. (4.10s and hilly country also).

 

Don't bet the farm on the computer readout. Sometimes they're accurate, and sometimes not. I've seen those number on my display too.<br><br>Here's what my actual fuel useage has been like: At the last fill-up I had put 9955 miles on the truck since I drove it off the lot with a full tank; I've filled it (26 times) with 583 gallons of fuel. That's 17.08 mpg. 75% city driving time. The high mpg tank was 20.5 (the only real mostly highway trip its been on); low mpg tank was 14.5 (middle of a cold January, I think idling here and there pulled mileage down). The computer readout on that high tank showed as high as 24 for much of the trip on the highway. Most fillups at a local Amoco Truck stop.<br><br>My fuel mileage trend analysis does not show any magical 2000 mile (or any other mile marker) radical change either way. In fact, there's minimal change. But my truck may not be broken in yet.

 

The computer has been a little optimistic most of the time.<br><br>So far - 5183 Miles on 278.5 Gal of fuel (14 tanks) for an avg. of 18.6mpg. This is a good mix of both city and highway.<br><br>The low tank was the first one at 17.1mpg and the high was 20.04mpg.<br><br>The last tank was a trip up to Quantico. 344 miles on 17.4 gal for 19.76mpg. Technally this is highway if you call anyware from 10mph to 75mph comming back down I-95 highway.<br><br>I'm real happy as this is better then the 17mpg that my old chuby C1500 with a 350 got.

 

[quote author=bulabula link=board=17;threadid=14583;start=0#137017 date=1052676874]<br>My fuel mileage trend analysis does not show any magical 2000 mile (or any other mile marker) radical change either way. In fact, there's minimal change. But my truck may not be broken in yet.<br>[/quote]<br><br>I'm now at 23,000 miles and haven't seen that change either.

 

Ig et very close to what bulabula is getting. Averaging 17.9 in town and I can get 20 on the road at 75mph. I can get 23 at 70mph and I can get 17 at 80mph. This is all by calculating miles and gallons manually and not relying on the computer. I have 4300 miles now.