MPG question about a 5.7l 2500

[01LSIMPALA]

I've got a 2000 Sierra Classic crewcab swb 4wd with a 5.7l/4l80e and 3.73's with factory size tires. I can't get any better than 12-12.5mpg with 90% highway/turnpike driving. Is this pretty typical with this combination? I have spent roughly $600 on add-ons (new 2.5" dual exhaust with balance tube, Jet power programer, and a K&N cold air intake) to try and improve mileage with no results. Any suggestions?

[mikey531]

Do you have a locking gas cap?? I have basically the same truck with 112000 miles and I get over 20 on the highway and around 18 in town and got around 10.5 towing my sons race truck in a 24' enclosed trailer. Everything is factory stock. Maybe check your speedometer/odometer to make they are reading correct.

[douglas92000]

Mikey could you explain to me how the locking gas cap would affect mileage? TIA

[mikey531]

well if someone was stealing your gas...

[01LSIMPALA]

Originally Posted by mikey531

Do you have a locking gas cap?? I have basically the same truck with 112000 miles and I get over 20 on the highway and around 18 in town and got around 10.5 towing my sons race truck in a 24' enclosed trailer. Everything is factory stock. Maybe check your speedometer/odometer to make they are reading correct.

No locking cap. I highly doubt that is the case considering where I park it and the fact that it is dead on consistent.

When you say "bassically" the same truck. What are your specs? I have seen a huge difference in mileage over a minor difference depending on what it is.

My speedometer is dead accurate with my GPS.

Anyone else running a 5.7l/4wd/3.73 crew cab 3/4ton?

[mikey531]

You are right my truck isn't like yours. I didn't see the 3/4 ton in your original post. sorry