2004 Buick Rainier Q&A

2004 Buick Rainier Question: 14.2 mpg highway & no error codes or lights

fuel mieage on local & highway, using high or low grade fuel, increasingly getting worse. Bought from dealer 1 year ago doing 16.0mpg, now down to 14.2mpg. no signs anywhere. mechanics won't look at it without a code to trace. -
Answer 1
Check this government website for 2WD Rainier. http://www.fueleconomy.gov/feg/findacar.htm They are not brilliant for MPG but some tires even can help fuel economy, (less rolling resistance). I wonder on a scan tool what the fuel trim figures are Long Term Fuel Trim figures show if your car's computer is adding or taking away fuel which may not yet have set a code. -
Answer 2
you may want to seek professional help because my 2006 AWD Rainer needed the stabiltrac serviced and after that the fuel mileage went from 15.7 to 19 mpg highway -