My tow vehicle is a 2004 Chevy.. HD 6.6L Duramax, 4X4 Ex-Cab, Allison Xmission, exhust system, opened up air system and power programer.
I pulled my last 5th wheel, a 31' high profile unit, close to 60K miles from coast to coast and border to border. My overall average was between 11 and 12...