I am in a very similar situation, I get 11 MPG (this is accurate I have tracked this for 8 months) and please read all the things that have been replaced on my 2008 Saturn Outlook...and also about the terrible problem with my fuel consumption, I get between 8-14MPG....read on...
I keep a very detailed Excel spreadsheet and track every single repair - since some of these repairs are multiple times! Anything in BOLD are pretty BIG repairs, engine had to be taken out...broken bolts that needed to be retapped in the head gasket...
Items Replaced Since July 2008:
Sensor Camshaft, Cylinder Head Gasket, Dead Battery, Windshield Wiper Motor, Transmission Software Update (after multiple concerns), Airbag Wire Harness, Power Steering Rack & Gear, Front Pads and Rotors (1st time), Gasket for Intake Manifold, Gasket for Rear Valve Cover, Right Front Strut, Both Strut Mounts, Engine Mounts,Front Pads and Rotors (2nd time), Left Front Stabilizer Link, Front Pads and Rotors (3rd Time), Headlight Harness, Airbag Connector Kit, Engine Front Cover Crank Seal, Timing Cover Seal, Broken Bolts in Cylinder Head & Valve Cover, Exhaust Stud, Broken Bolts, Power Steering Pump, Hose & Clamp.
I am also going to try and post an excel chart, so you can see the MPG from Jan - June 2012 (6 months). This is AFTER the Transmission Software update (done in 2009)....no wonder I am going broke on GAS!
Date Odometer TripA Gallons Cost MPG/tank 1g gas
20120131 45811 211 16.76 $66.00 12.6 $3.95
20120202 46022 203 17.01 $65.00 11.9 $4.35
20120205 46225 189 18.01 $67.80 10.5 $4.21
20120210 46414 169 19.01 $85.65 8.9 $3.89
20120215 46583 176 19.02 $52.55 9.3 $3.79
20120222 46759 214 19.71 $67.81 10.9 $3.99
20120227 46973 221 18.42 $78.03 12.0 $4.19
20120229 47194 195 19.32 $74.50 10.1 $4.15
20120305 47389 213 18.69 $70.99 11.4 $4.11
20120312 47602 199 18.42 $75.02 10.8 $3.65
20120317 47801 173 18.74 $50.00 9.2 $4.01
20120319 47974 197 18.15 $69.32 10.9 $4.03
20120324 48171 228 18.67 $75.00 12.2 $3.99
20120331 48399 223 19.13 $76.19 11.7 $3.94
20120402 48622 201 18.51 $55.00 10.9 $4.02
20120407 48823 189 19.71 $60.01 9.6 $4.05
20120411 49012 167 14.85 $65.09 11.2 $3.97
20120415 49179 284 19.51 $44.11 14.6 $3.92
20120417 49463 176 19.51 $62.60 9.0 $3.99
20120423 49639 221 18.11 $74.71 12.2 $4.01
20120425 49860 170 19.13 $60.01 8.9 $4.05
20120507 49573 211 18.51 $85.00 11.4 $4.09
20120514 50112 174 17.21 $68.67 10.1 $3.99
20120514 49789 216 18.11 $72.11 11.9 $3.93
20120520 49790 224 16.76 $65.20 13.4 $3.89
20120524 50014 260 17.51 $61.24 14.8 $3.50
20120529 50286 238 19.71 $76.42 12.1 $3.88
20120604 50524 197 14.85 $55.85 13.3 $3.79
20120610 50721 204 19.51 $75.00 10.5 $3.86
20120616 50925 176 19.51 $75.00 9.0 $3.86
20120622 51101 211 18.11 $65.60 11.7 $3.65
20120630 51312 190 18.67 $74.87 10.2 $4.01
20120707 51479 187 19.24 $71.95 9.7 $3.73
AVERAGES 204.19 18.34 $67.82 11.1 $3.96
GM GAS CONSUMPTION ESTIMATED MPG City 16 Highway 22 AVERAGE 18
KM GAS CONSUMPTION ESTIMATED MPG City 9 Highway 15 AVERAGE 11
Difference of MPG: Advertised vs. Actual - 7MPG
Total Miles Driven with Updated Software - Current Miles 51k
At Software Update 9300 Total Miles 41,700 Driven with software update
Total Gallons of Fuel Required for 41k @ 18MPG - GM 2317 gallons .....Cost of Fuel $8692
Total Gallons of Fuel Required for 41k @ 11MPG - KM 3791 gallons......Cost of Fuel $13761
Difference of 1474 gallons and $5837 in excess fuel!!
On Average, the cost of that update Per month costs me $153 in fuel each month.