i have a 05 auto i6 w 31 tires i changed speedo gear it runs around 1800 rpm at speed limit mpg is horrible around 13-14 i have heard that the i6 gets better mpg at 2200-2600 what do you think also does headers or cold air intakes help with this does anyone have any suggestions
09-08-2008 02:52 PM
I don't believe the headers or cold air kits do much for mpg. Face it, we drive vehicles that have the aerodynamics of a brick driving down the road. You may want to get it scanned and see if any codes are being stored that would lead the vehicle to be running rich. I think your truck should be getting in the neighborhood of 18-19 mpg, but with the tires and stuff I'm not really sure. Sorry I can't be of anymore help.
09-08-2008 03:11 PM
best HP to gas mileage is in the 2300-2400 rpm range so that could be part of the reason why