Gas Mileage :(

[Gr8ride]

Originally Posted by Evergreen6

We need to know more about your driving habits and also how you came up with 11mpg.

Also, not sure that a CAI would affect your mileage much, but maybe you somehow messed with the MAF?

It's been discussed at length regarding fuel octane, but you are absolutely wasting money by putting higher octane fuel in your v6.

I drive mostly city near 8 miles a day and some highway during the weekends. im easy on the pedal, and I dont race from one light to another. In other words I baby my car and do mostly short drives with lots of red-lights.

as far as the 11 mpg, I just see how often I have to fill up the first 1/4 of the tank, usually under 35 miles for around 4 gallons of fuel.

[Squillo]

If you're mostly city driving that's probably got a lot to do with it, but 11 seems way low even for that. The red lights could be what's killing you.

EDIT: just noticed you're in Florida. Red lights and A/C are probably what's killing you. You're guaranteed to get 0 MPG while sitting at a red light, and it's even worse with the A/C on.

[ChrisBlair]

Originally Posted by Gr8ride

I drive mostly city near 8 miles a day and some highway during the weekends. im easy on the pedal, and I dont race from one light to another. In other words I baby my car and do mostly short drives with lots of red-lights.

as far as the 11 mpg, I just see how often I have to fill up the first 1/4 of the tank, usually under 35 miles for around 4 gallons of fuel.

I think the terms "city" and "highway" are confusing, for starters. Just how often are the stops and starts calculated for those ratings, and what acceleration was used to start? It seems nobody knows.

But in your case, remember a few things-

1) Squillo makes an excellent point: all cars- all of them- get the same gas mileage when stopped. In other words: zero MPG. You're burning gas and not going anywhere. Some wag will say "A hybrid does X Y and Z". Very good, but the car is still not traveling any distance when stopped. By definition: zero miles per gallon of fuel, even if the electric drive is in control. No gas used but no miles gained is still zero MPG. Same as if I turn my car off at night and park it: zero MPG!

2) Your drive requires that you stop many times. You also never get into any real cruise- you're starting and stopping starting and stopping. I understand you're paying attention to the gas, not the DIC, but the DIC will show you an average MPG, not current MPG, which is too bad because current MPG could give an indication of where drivers are being wasteful on gas, and this might answer your question easily. Anyway, your overall city MPG must have all those zeroes tossed in the calculation from when you were stopped. You might see a peak of say 17 MPG in your stop and go stop and go drive. You get hosed by all the zeroes though, because by DIC or by hand calculation, the gas was still burned while you didn't go anywhere.

Here's an example of how those zeroes screw you over. Let's say that your drive is just one minute long, and the overall MPG is calculated once per second. For 30 of those seconds you are stopped. For thirty of those seconds you get 20 MPG. (This ignores the fact that as you speed up you will get worse MPGs than 20). The average works out like this:

60 total data points
30 data points at 20 mph = 600 units
30 data points at 0 mph = 0 units
Total= 600 units
Units / total data points = average
600 / 60 data points = 10

So 10 MPG average, even though in the case of our fictional car it was capable of 20 mpg between stoplights. Although it was capable of that MPG it could not achieve it because it was stopped as often as it was moving, all the while burning fuel. The average is your reality.

3) Try driving the same route at 3 am and compare your results.

[SSGUNNER]

Originally Posted by Squillo

If you're mostly city driving that's probably got a lot to do with it, but 11 seems way low even for that. The red lights could be what's killing you.

EDIT: just noticed you're in Florida. Red lights and A/C are probably what's killing you. You're guaranteed to get 0 MPG while sitting at a red light, and it's even worse with the A/C on.

I get 14 ish on my SS with ac on sitting in traffic at 10-15 mph on a 20 mile ride mon-fri. At higher speeds i'll stay around 16 ish.

So there is an issue somewhere.

[Squillo]

Originally Posted by ChrisBlair

I think the terms "city" and "highway" are confusing, for starters. Just how often are the stops and starts calculated for those ratings, and what acceleration was used to start? It seems nobody knows.

But in your case, remember a few things-

1) Squillo makes an excellent point: all cars- all of them- get the same gas mileage when stopped. In other words: zero MPG. You're burning gas and not going anywhere. Some wag will say "A hybrid does X Y and Z". Very good, but the car is still not traveling any distance when stopped. By definition: zero miles per gallon of fuel, even if the electric drive is in control. No gas used but no miles gained is still zero MPG. Same as if I turn my car off at night and park it: zero MPG!

2) Your drive requires that you stop many times. You also never get into any real cruise- you're starting and stopping starting and stopping. I understand you're paying attention to the gas, not the DIC, but the DIC will show you an average MPG, not current MPG, which is too bad because current MPG could give an indication of where drivers are being wasteful on gas, and this might answer your question easily. Anyway, your overall city MPG must have all those zeroes tossed in the calculation from when you were stopped. You might see a peak of say 17 MPG in your stop and go stop and go drive. You get hosed by all the zeroes though, because by DIC or by hand calculation, the gas was still burned while you didn't go anywhere.

Here's an example of how those zeroes screw you over. Let's say that your drive is just one minute long, and the overall MPG is calculated once per second. For 30 of those seconds you are stopped. For thirty of those seconds you get 20 MPG. (This ignores the fact that as you speed up you will get worse MPGs than 20). The average works out like this:

60 total data points
30 data points at 20 mph = 600 units
30 data points at 0 mph = 0 units
Total= 600 units
Units / total data points = average
600 / 60 data points = 10

So 10 MPG average, even though in the case of our fictional car it was capable of 20 mpg between stoplights. Although it was capable of that MPG it could not achieve it because it was stopped as often as it was moving, all the while burning fuel. The average is your reality.

3) Try driving the same route at 3 am and compare your results.

I have indication of instantaneous actual MPGs in my car. On acceleration in lower gears it's <4 MPG, on hard acceleration it's <1MPG.

Also the car calculates the MPGs more than once per second. It's hard to tell by how fast the thing updates, but it's at least every 0.2 seconds.

[ChrisBlair]

Originally Posted by Squillo

I have indication of instantaneous actual MPGs in my car. On acceleration in lower gears it's <4 MPG, on hard acceleration it's <1MPG.

Also the car calculates the MPGs more than once per second. It's hard to tell by how fast the thing updates, but it's at least every 0.2 seconds.

You have instant MPG? Is that a 2SS feature or is that a model year feature?

I never suggested that the calc is done every one second by the car. In my example I am careful to avoid "average" being associated with the calc even though that's what I'm really doing, for that reason . I do not even care if the calc is done by the car or by hand somehow. It's simply an example with easy to use numbers for the sake of illustration- I don't want to use tens of thousands of data points in an example

[Squillo]

Originally Posted by ChrisBlair

You have instant MPG? Is that a 2SS feature or is that a model year feature?

I never suggested that the calc is done every one second by the car. In my example I am careful to avoid "average" being associated with the calc even though that's what I'm really doing, for that reason . I do not even care if the calc is done by the car or by hand somehow. It's simply an example with easy to use numbers for the sake of illustration- I don't want to use tens of thousands of data points in an example

No, I bought a DashLogic from www.palmerperformance.com.

I love this thing it's a great tool / toy.

Check this thread for info: http://www.camaro5.com/forums/showthread.php?t=348660

[ChrisBlair]

That's cool....and 250 bucks. How did I miss this???

Shut up and take my money!

[wadeh]

Originally Posted by ChrisBlair

1) Squillo makes an excellent point: all cars- all of them- get the same gas mileage when stopped. In other words: zero MPG.

It's certainly true that all cars get zero MPG when stopped. But not all cars are equal in this regard. The "gallons" part of miles per gallon is important. A car that burns more fuel while stopped will be hurt (in terms of MPG) more by time stopped than one that burns less fuel.

Another real killer is accelerating from a stop. Depending on your right foot, that may be a bigger factor than idling while stopped.

And for the OP, another factor is the short commute. In my SS, the oil doesn't really reach full temperature until about 5 miles of driving. In the case of an 8 mile commute, that means that about 60% of the distance is with the car not fully warmed up. That will make a big difference in economy.

[Squillo]

Originally Posted by wadeh

It's certainly true that all cars get zero MPG when stopped. But not all cars are equal in this regard. The "gallons" part of miles per gallon is important. A car that burns more fuel while stopped will be hurt (in terms of MPG) more by time stopped than one that burns less fuel.

Another real killer is accelerating from a stop. Depending on your right foot, that may be a bigger factor than idling while stopped.

And for the OP, another factor is the short commute. In my SS, the oil doesn't really reach full temperature until about 5 miles of driving. In the case of an 8 mile commute, that means that about 60% of the distance is with the car not fully warmed up. That will make a big difference in economy.

100% true

[mariojmoe]

There is clearly an issue there bud. I keep my foot nailed in my ss ls3 manual with both city and hwy mixed i never drop below 16 combined at worse. You are in heavy foot Zl1 mpgs there

[007s 'Vert]

I used to get excellent mpgs, but that was when I was doing mostly freeway driving and long commutes.
Now that I live in Vegas with a mess of stop and go traffic (mostly stopped) my mpgs dropped quite a bit, I went from 30+ mpgs to 20 average in my old hard top.
Now that I have this new Vert, I am getting 16~18 in city driving, doesnt bother me at all though, it is a heavier car due to all tbe weight added for the vert, and since I have the top down all tne time, it seems to add more drag to the car, I went from 18 inch wheels/tires to tne 20 inch wheels/P-zeros, which IMO create more drag, and living in the desert I use the AC more. So all these things you have to factor in.
Like someone else mentioned in here before, find yourself a nice straight road/freeway that goes quite a ways and test tbe car out on it, I did........I got on the freeway here and got cruising at aroung 70 mph and then reset the DIC, I cruised about 20 miles, and at the end of the cruise it was showing 28 mpg average......and that was with the top down....... im happy, it showed me nothing is wrong with the car, the driver needs to re-assess his driving habits/skillz.
I know for a fact that I could drive your car and sqeak out 30+ mpgs if given the chance, unless there is something wrong witn your car mechanically.
Heck, I reset my DIC one time before I took a cruise up the Vegas strip on a Saturday night.........at yhe end of tbe cruise I was showing 5.5 mpgs.....lol......that was a situation where u gotta chaulk it up to "smiles per gallon"

[Gr8ride]

Thanks for all the great Info guys, I wish I could provide harder data to support what I have said, but the DIC says I average 16 mpg. Next time im at the dealership Ill ask them to check and see if there is any other issue that might be causing this.

[skibik]

If you want to be more accurate on your MPG first off manually calculate out miles/gallons used. Second, a quarter tank fill is not a proper calculation for figuring a good average MPG. Run it to around a 1/4 tank then fill and then manually calculate it. At a quarter tank fill you aren't going to be as accurate. If you fill at one stop and put 4 gallons in and let the nozzle click off and put the nozzle back and on the next 4 gallon or so fill you squeeze the handle a few more time and say you got in that extra half gallon this will throw you figure off because it wasn't filled to the same place as the last tank. You need to burn more out of the tank and then try to fill it to the same place each time to get an accurate MPG calculation.

Dean.