I have a Chevy 2002 HD1500 with a 6.0L with a Bullydog Power Pup Gas and I got 1.2 MPG better than stock on regular setting. I have been playing with multiple settings and fuels. With 91 octane premium and the perfomance setting I actually lost about 4 MPG. I was told to try lower octane as higher octane fuel burns slower.
The EPA mileage estimate for the 2004 GMC Sierra-1500 is 14 mpg in the city, 19 mpg on the highway.
The EPA mileage estimate for the 2014 GMC Sierra-1500 is 18 mpg in the city, 24 mpg on the highway.
The EPA mileage estimate for the 2001 GMC Sierra-1500 is 14 mpg in the city, 18 mpg on the highway.
The EPA mileage estimate for the 2006 GMC Sierra-1500 is 14 mpg in the city, 20 mpg on the highway.
The EPA mileage estimate for the 2005 GMC Sierra-1500 is 14 mpg in the city, 20 mpg on the highway.
The EPA mileage estimate for the 2012 GMC Sierra-1500 is 15 mpg in the city, 20 mpg on the highway.
The EPA mileage estimate for the 2011 GMC Sierra-1500 is 15 mpg in the city, 20 mpg on the highway.
The EPA mileage estimate for the 2013 GMC Sierra-1500 is 15 mpg in the city, 20 mpg on the highway.
The EPA mileage estimate for the 2008 GMC Sierra-1500 is 15 mpg in the city, 20 mpg on the highway.
The EPA mileage estimate for the 2003 GMC Sierra-1500 is 14 mpg in the city, 19 mpg on the highway.
The EPA mileage estimate for the 2007 GMC Sierra-1500 is 14 mpg in the city, 19 mpg on the highway.
The EPA mileage estimate for the 2002 GMC Sierra-1500 is 15 mpg in the city, 19 mpg on the highway.