Driver Information Center - Very very Poor Accuracy

Purchased a 2002 Impala with a Driver Information Center (U68) option. Measured 'fuel used' (Gallons) accuracy by recording fill-up gallons for each filling station stop for 2 years & reset to zero after each fill-up. the THE AVERAGE INSTRUMENTATION ERROR has been 30% !!!! When the fuel used readout shows 10 gallons - it REALLY used 13 gallons! 30% ERROR! ALSO - since the MPG average and instantaneous MPG uses the fuel used data with the odometer distance data - THE MPG shows a 30% ERROR in GM's favor! If gauge shows 20 MPG - you are really doing 30% LESS! GM stated that this is satisfactory measurement accuracy! Since when, for almost any instrumentation package, can the accuracy be essentially WORSE than the regular gas gauge analog readout on the dash. I have had other fuel flow meters on other cars and thay have been very accurate! I checked with my friends, and their cars were very accurate. 1% 2% type of accuracy - NOT 30%!

Suggest that everyone out there with an instrument option - measure the accuracy. You may be very surprised if you have an Impala. Filling station pumps have to be accurate to meet State standards.

Why pay extra $$$$$ for an instrumentation option of 30% accuracy?

What should I do to get the above calibrated/fixed?

At the present time, GM WILL NOT FIX - or even attempt to recalibrate! The fix for this is NOT that complex!