I know most don't care about mileage on here but mine is a DD so I still do. I've had the 99 for 2-3 months now. Ran about 10-12 tank fulls of gas. Same station usually, same angle, ck my mileage carefully, always 15.5 to 15.8. Got 16 once when I took a short trip. After changing to efans and 3.90's from 3.42's this week I took another short trip, 140 miles. Averaged 74 mph as usual...21.67 MPG! Same 30" tires. Even last week, 15.8 MPG!

 

:crickets:

 

Well that sucks avg is 15.6 mostly in town driving and my highway is more towards 18\19 with mods in sig plus extra hundred pounds in tools

 

My truck is the same way. Only gets 14-16mpg driving around town. Once I hit some highways or out in the country away from traffic and stoplights I can usualy get 18-20mpg. Having 20" wheels and almost 32" tires with 3.73s doesnt help much in my case either. When I run my 18" wheels and 30" tires I can see 1-2mpg better on average.



wooohooo 1500 posts!

 

20.4mpg right now mods in sig

 

Looks like your cam and 4wd maybe? Still good. Mine is 2wd with 5-600lbs of AC tools and parts. Getting a tune next week!

 

Since its a 99 have ur tuner do lean cruise made big difference in mine no cam but 4x4 little more heavy and I'm not bashfull either I drive mine like I stole it

 

Thats a good improvement!

 

I went from 15mpg to 22mpg after the T56 swap with the 3.73's and a basic tune. But then I swapped gears to 4.56's and it's back to 18mpg with 75/25 highway/city. Cammed trucks with a good tune seem to get decent mileage. Also if your tuner has EFI Live ask about getting lean tune enabled.

 

5.5 mpg gain from gears and efans. Id say thats awesome man! Now think you can save money to buy more mods....

I think mine gets 16 i dont remember but thats also with 4.88's and 3800 stall.