What is a good crusin speed on the highway to get max fuel econ. Right now i drive about 100 miles every few days, and i have a little heavy of a foot and i drive about 77 or 78 on the highway and i get only about 14 or 15 mpg. Any suggestions. I have an 03 Ext 5.3 Z71. Any ideas on how to get a lil more fuel economey?? thanks in advance

 

I try to stay around 72-75mph, no floor-boarding around the slow people. Also my Nelson tune made a nice inprovement. On the highway I get 18-19mpg....when I want to . I was getting about 16-17 before, which was still pretty good. The 03 QC Hemi I had never saw anything over 12

Jay

 

65-70mph tops is best for me. I get about 16.5 avg if I cruise 65mph on the freeway and 15.5 avg if I cruise 70mph on the freeway...this is mixed with mostly freeway.

Only city is about 15mpg and only freeway is right about 20mpg.

But remember I drive slow on the freeways. You drive a BOX not an aerodynamic car, drags increases exponentially as speed increases hence the fuel economy loss.

ALSO, this came only after my custom tune. My best was right about 17mpg freeway only stock tuning.

 

65-70 works for me as well. i usually get 14-15 depending on how i drive. sometime even 16 or higher if it is mostly highway...

 

i just drove to and from mississippi and back. 442 miles on each tank. and that is driving 80 to 90. averages out to around 18.2mpg. and this is the second trip with the same results. nelson tunes---

 

Oh I forgot to mention that I have 3.73:1 gears and 285 ATs on the truck so my cruise RPM is too low... 70mph @ 1800rpms sucks.

 

Damn Sounds like the nelson tune helps out a helluva lot. Looks like it is time for Hypercrap to go up for sale.

 

Yeah nothing beats custom tunes.If I cruise at 70MPH my tach is at 2250 RPM and I pull about 15.If I keep my speeds down to 63-65 then I get about 16MPG,I also have a 350 though.They use more than the new engines.

 

All tuning helps, but a custom one is better.

 

Those bigger tires are probably(sp?) killing 1-2mpg...But they sure do look good. I'm trying to talk myself out of a set right now.