IMPALADAKID

My 09 2.2/auto LS panel seemed to be accurate. I would reset the trip, and the MPG on the DIC, and actual was within a .5 mile difference, and that started with the first tank of fuel the dealership put in at 17 miles. 5K later, that did not seem to change. Still fairly accurate. I averaged 29.5 on the DIC, and real world was 29. Move forward to now, I have a used 07 2.4/auto with 87k on it, and according to the DIC, I am averaging 32 mpg. I am calling foul. Mostly because of the mileage (coming up for first tuneup in less.) I drive itwith the average mileage up all the time to keep myself in check, but 32 mpg average seems high. Driving is 60/40 city/hwy.

Thank you

jered6323

I've been using an App for the iPhone called "Gas Cubby" to keep track of all my fill ups/repairs for all my vehicles. It automatically calculates the mpg for you, which is nice. But if you want to do your own calculation, when you fill up with gas, just divide the miles you've driven since the last fill up by how many gallons you've put in.

Example: 305 miles divided by 13.169 gallons = 23.16 mpg.

IMPALADAKID

I do calculate at fill ups. I fill up, and reset the trip, then calculate at next fill up. I have always done that. But with just 8 days, and 250 miles with my HHR, I am just below 1/2 a tank. I will probably fill up today just to see how close, but it just seemed too high to be true.

Thanks for the heads up on the app. I will check it out.

Snoopy

IIRC....

The first HHR's (06 and 07) highway mileage had higher EPA (STICKER) ratings.

jerSSey HHR

Why would you manually check your MPG each time if you can get that from the DIC? I can see comparing them from time to time to calibrate, but why do it each time? I used to do that with my first car many years ago (before DICs), but it got to be so time consuming. One of my co-workers actually inputs all his data into a spreadsheet to track all the MPG data, including the price of gas so he can translate to dollars/gallon.

Laco

IMO the DIC is pretty accurate. The few times I have checked, it, and my calculations were within a couple tenths of a MPG, well within a range of what I would consider filling to slightly different levels.

badassbowtie

I feel like the DIC is 99.9% accurate. Yea it seems to be off but I believe its human error. When you fill up, and the pump clicks off, do you go to the next dollar? Fumes can make the pump think its full. I think the only variation we get when manually calculating mileage, is from a different amount of gas being in the tank when "full"

5speed4

When I first got my '06 2LT (5-spd manual), the DIC consistently measured low (by as much as 1.5 mpg). As I've owned my '06 for over a year now, I'm finding that the DIC seems to be more accurate than it was when I got it. I don't know if it's possible, but I think it's getting more calibrated to my driving style. Now it's almost dead on.

kornellred

If the inputs to a computer are accurate, and the calculation algorithm is valid, then the computer can only give you a correct answer to a calculation if it is functioning. It cannot produce an incorrect result.
The computer has, stored in memory, a file which contains data on how much fuel is injected by each injector for each specific pulse duration. The computer knows, with precision, exactly how much fuel has been burned from the moment the engine is started until the engine is shut off.

Assuming that a vehicle has the same outside tire diameter that it had when it left the factory, the distance the vehicle has traveled during a particular drive is also calculated with acceptable precision.

The computer does what the driver does, only with far more accuracy: it divides the distance traveled by the amount of fuel consumed and produces a figure of merit known as "miles per gallon".

It's that simple.

badassbowtie

X2. exactly what I was getting at....the only error would be human error.