[KManzi]

Hi there...please re-think having the Transmission callibration software update done...this has cost me over $5800 in excess fuel since 2009.
I am in a dispute with GM, they have done nothing for me and I have a LONG list of repairs since Ihave owned it. I promised GM I would let everyone know about this, so I do apologize if I am leaving anything out because I have told this story so many times!

After years of TERRIBLE Fuel consumption...I decided to track it, every fill up, for 8 months... Here is a 6 month snapshot...I get on average 11 MPG.

Columns in order go: Date, Mileage, Trip A, Gallons Filled at Pump, Cost of Fill Up, MPG, Price Per Gallon.

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.
But without the software update, I was nearly rear ended several times because of the flat spot / lack of power and hesitation on the highway.


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.

 

[KManzi]

I don't have shift points like that, but I do know that in the higher speeds it definitely revs more before shifting...even after the software update. I feel like I am pulling a parachute all time, when you let off the gas, you almost fall forward - it's not like you let off the accelerator and coast....believe me, I know it does not operate properly, I do drive 70mph on the hwy, but at least on cruise to reduce the accelerating and braking...

But....I have traded it in as of today, I can no longer let this consume my time, GM didnt want to keep me as a customer and offer a complimentary repair coverage due to the fact it is a lemon, with so many major repairs, and more importantly, GM would not reimburse my excessive fuel consumption - which is certainly not what was advertised on the window sticker. I can see if it was a 2-3-4 mpg difference, but I am at a 7mpg difference, almost HALF of what they advertise!

GM left me no other options but to trade my car in, but at least I didn't fall for the bait and switch again....I will never be a GM consumer again. Why on earth would I buy another GM even if they offered me $3k towards a new car...that really isnt alot when you break it all down.