I am a huge proponent of the in dash AVG MPG meter in the dash and have now proven that it is accurate. This weekend, I drove from a suburb of Akron, OH to Buffalo, NY and went through a full tank of gas on the round trip. I was surprised the car made the trip there and back on just one tank of gas. The mileage meter said 35.2mpg and I did the hand calculation which proved to be exactly the same. I was disappointed in the 35.2, but it was with the cruise set at 70mph and the transmission set in manual mode in 6th gear (auto trans car). This car continues to impress me each day. I actually prefer driving it now when compared to the CTS-V in the garage!
For those that doubt the AVG MPG meter in the dash....
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What did you base your hand calculation on? Not to be too doubtful, but I can't tell you how many people I've seen tell me that they used the "gallons used" number on the DIC to calculate their average fuel economy without actually filling up and seeing how many gallons fit in their tank.
One hand calculation that matches the DIC once does not disprove the 100s of hand calculations that are always shy of what the DIC represents. I track every fill-up on Fuelly, and every single one has been shy of the DICs readings. One or two hand calculations can be wrong, but not when I'm talking 20-30 fillups all being shy. I think most everyone else who has done multiple hand calculations of mileage has found them to be shy as well.
The DIC is, by and large, inaccurate and optimistic.
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In steady speed driving on flat ground the fuel used estimate is probably very accurate. Otherwise, the technique GM uses to measure the fuel consumed is optimistic anywhere from 2 to 10 %, causing the DIC's Average MPG to read high by 2-10%. The problem is that GM doesn't count injector pulses, which is the only way to get an accurate measure of fuel consumed.
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Mine has never been closer than 5% on the optimistic side. I've logged every fillup. No one fills my tank but me. Same pump/station, and 90% of the time, same time of day...early am.
Mine ranges from 5% to 11% optimistic...I've learned to live with it, and use it for "Indicating Purposes Only", that is, when the DIC is reading in the mid 40's, I know I'll get about 39MPG; haven't
broken the 40MPG barrier yet!
Mine ranges from 5% to 11% optimistic...I've learned to live with it, and use it for "Indicating Purposes Only", that is, when the DIC is reading in the mid 40's, I know I'll get about 39MPG; haven't
broken the 40MPG barrier yet!
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858 Posts
Fuelly is a great tool. However, if you have not used it for every single fuel up including entering the tank the dealer put in when you bought the car then of course it's gonna be off. Your DIC is accounting for EVERYTHING so if fuelly isn't doing the same it wont be exact.
I personally did the calculations by hand for the first approx 7600miles. Using the gallons i put back in as displayed on the fuel pump divided into the mileage i had put on the car since the last fill up. And it was never more than .2mpg off. At about 7600 miles i got a fuelly account and have used it for 4 fill ups so far and it reads 1.3mpg higher than my DIC. This being because as i have driven the car more, I continue to learn how to get better and better mileage out of it. So on my 1.8 LS I have no complaint about the DIC MPG readout.
I personally did the calculations by hand for the first approx 7600miles. Using the gallons i put back in as displayed on the fuel pump divided into the mileage i had put on the car since the last fill up. And it was never more than .2mpg off. At about 7600 miles i got a fuelly account and have used it for 4 fill ups so far and it reads 1.3mpg higher than my DIC. This being because as i have driven the car more, I continue to learn how to get better and better mileage out of it. So on my 1.8 LS I have no complaint about the DIC MPG readout.
I started using Fuelly with 78 miles on my car. I have also tracked it with the DIC and the Torque application. Torque is always 1 - 2 mpg low and the DIC is always 2 - 5 mpg high. If you fill up at the same pump and use the same steps when you fill up it is hard to get that hand calculation wrong. I have put almost 8k miles on my car since I bought it Feb. 21st and this has always been the case. I am not surprised though because this has been the case with every vehicle that I have owned with a mpg calculator on it.
Another thing, I reset my trip2 each time I fill up and trip1 has never been reset and shows the exact same mileage as my odometer and my trip1 mpg is almost 39mpg over the 8k miles. You can look at my Fuelly and see that I have never been close to 39mpg and over 20 hand calculations like that you wouldn't be wrong every time.
Another thing, I reset my trip2 each time I fill up and trip1 has never been reset and shows the exact same mileage as my odometer and my trip1 mpg is almost 39mpg over the 8k miles. You can look at my Fuelly and see that I have never been close to 39mpg and over 20 hand calculations like that you wouldn't be wrong every time.
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93cobra -- many of us have not had the same results as you got. Here's our 2011 LTZ's DIC-vs.-PUMP numbers after 51 fillups:
...notice our "cluster" around 0.95-0.96-0.97 which accounts for half of all our fillups.
| 0.89 | 1 | ■ |
| 0.90 | 0 | |
| 0.91 | 4 | ■■■■ |
| 0.92 | 2 | ■■ |
| 0.93 | 8 | ■■■■■■■■ |
| 0.94 | 4 | ■■■■ |
| 0.95 | 8 | ■■■■■■■■ |
| 0.96 | 9 | ■■■■■■■■■ |
| 0.97 | 8 | ■■■■■■■■ |
| 0.98 | 2 | ■■ |
| 0.99 | 0 | |
| 1.00 | 0 | DIC = pump |
| 1.01 | 2 | ■■ |
| 1.02 | 0 | |
| 1.03 | 2 | ■■ |
| 1.04 | 0 | |
| 1.05 | 0 | |
| 1.06 | 0 | |
| 1.07 | 1 | ■ |
| 51 |
...notice our "cluster" around 0.95-0.96-0.97 which accounts for half of all our fillups.
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Setting the transmission in manual mode while running on Cruze control won't do diddly to improve mileage. The transmission is still using the same gear and torque converter. All manual mode does is to allow you to choose when to shift.
I've done long distance drives at 70 mph and got as good as 38.5mpg in my 2LT.
I've done long distance drives at 70 mph and got as good as 38.5mpg in my 2LT.
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858 Posts
Correct, however it does force the vehicle to stay in 6th even on a light grade where the computer may decide it wants to shift to 5th, and you know it does not need to. In theory it could save minimal amounts of gas depending on the situation and the route.
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93Cobra,
Thank you for sharing this feedback! I am also very happy to hear that you love driving your Cruze so much! If you ever have any questions, comments or concerns please feel free to contact me anytime. I am always happy to help! Again, thank you for sharing.
Thank you,
Stacy Chevrolet Customer Service
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