peterbilt 387 mpg?

Like they said,.. between 5 - 6.5 depending on speed, load, driving habits and how much you idle.

Personally I think it could be as low as 4.5 if you run near gross most of the time, especially with a heavy foot.

I run a C15 with 13 spd (3.36 rear) and shift between 1350 - 1450 depending on terrain. Climbing a long grade near gross weight, I am more apt to ride out the rpms between shifts. Though I dont down shift until between 1100 - 1200. C15 will still pull hard at 1200 rpm. I may even ride it down to 1000 rpm if I am near the crest.

Idling 8 hours can cost as much as a hotel room for the night. Fact.



Hurst

 

at 60mph, idling at night, 2001 freightliner with detroit 12.7L engine pulling around 40k loads on average, i get around 7 mpg total monthly average.

 

The old 387 I was driving had a isx fuel mileage was 6 @68 mph.

 

You said C15 single turbo. I'm guessing an 04 with a bridge engine. Nothing wrong with your shifting rpms if you are not in the hills. As far as mpg probably 5.6 to 6.4. if it's an older C15 you might get a little better but not much.