I am getting 18.3 mpg avg right now, and 23 mph avg.

But, Bank 2 Sensor 1 Oxygen Sensor is shot, which means my engine is running rich. I have definitly noticed the difference in gas costs.

When i first got my Z i was getting around 13 mpg with the same avg mph. The trick i found is shift early when you dont need the power.

Around the city i take first to about 8-10 mph. after that, i never let the engine rpm's get above 2500 and shift into 6th gear as early as possible.

Although it is so much fun when you put that accelerator all the way down and take it to red, around the city, its too inefficient. Remember, bigger engine displacement= more gas burned. plain and simple.

try playing with your shift points and such, see if it makes a difference. the longer you leave the Avg mpg/mph unreset, the less fluctuation you will see in the numbers. so if you try a new shifting technique, be sure to reset it and drive for a few days to see if it makes a difference.

 

Make sure you don't bog it down. Try keeping the car in a decent RPM range on hills and stuff.

I give it a little gas when I drive and I still get just under 23.

 

?????????????????

And drag increases in direct proportion to speed.

So how can speed not have anything to do with it?

 

Hmm something is wrong with ur car.

 

my avergage speed for my past two tanks has been 26 mph... (all city) im averging 15 mpg stock

 

I'd love to get 15 mpg. My nearly unmodified car gets less than 13 mpg over the two years I've owned it. It's rarely out of stop-n-go traffic light to traffic light driving in the city.

 

It's not a direct proportion; it's exponential. Velocity is squared in the drag equation. Meaning that twice the speed exerts 4 times the force in aerodynamic drag.

Furthermore, when you look at the POWER needed to overcome aerodynamic drag, velocity is cubed. Meaning that twice the speed requires 8 times the power.

http://en.wikipedia.org/wiki/Drag_equation

 

^ he's exactly right. it is a squared function relationship. glad to see other brains on board


without getting too much into physics... i'd like to say i average 19.8 mpg and half of my driving is on the highway... so... city should be like 16ish for me. and 24 ish on the highway

 

....for the reasons I explained in the rest of the post that you didn't quote.

I'm surprised you are having problems with this one, bill. Maybe you're trying to confuse instantaneous mpg with average mpg.

Speed is not a function of average MPG. Even with 3rd grade math you can figure it out.... and nowhere do you need to supply your speed. It's simply a matter of fuel used vs distance traveled. Fuel used takes into account everything that required the fuel usage, no matter how complex, whether it be speed, load, gear, parastic drag, etc.

Don't make it more complicated than it really is....

 

Your avg. speed may not have any affect on how you calculate your fuel economy, but it can be an indication of what kind of driving you've been doing. If your avg. speed during a month is 32mph, you've been doing a lot of city driving. Which means you've been using gas while stopped at a light, and wasting gas slowing down and speeding up constantly. You should expect lower MPG if your avg. speed is low just because you've been doing stop-and-go driving. I'm not aware of any place where you would go 20mph for a couple hours at a time without ever wasting gas by using your brakes.

 

I totally agree with the point you're making.

 

06 A/T here and I get 23-25mpg getting on it all the time 90% city driving and using the (what ever you want to call it, manumatic). Driving with the automatic side on highway is a whole different story. 23-25mpg is worse case scenario that I've gotten ever. Right off the bat I put a full K&N CAI and noticed a difference in a few things including MPG. I have 2500 miles on it so far.

 

i have an 06 roadster touring... and i use cruise control alot.... 2/3 highway, 1/3 city. most of the time i just cruise on the highway, but i floor it from time to time to play with other people or... entering an empty highway ramp... vrooom!

my mpg is 19.1mpg at 36mph .... if only i had a coupe, i think i would have had a much better mpg -_-

 

I get 26-28mpg on a regular...but my commute is 47 miles each way, mostly highway (65-70 mph) and the last 10 miles lots of stops.

 

my Z gets much better mileage than my SUV... no complaints

 

Yeah, if the car is brand new, it's still in learning mode. The computer needs about 2 months to get used to your driving. When I reset my ECU (unplugging the neg cable on the battery) I got like, 9 MPG. But the next tank of gas was much better.

 

i have only test pipes and air intake and my mpg is 14-15 av mph is 26(6 speed)

 

I'm kind of having the same problem also, I get 16.6 MPG at 20 AV MPH. I think its becuase of the city driving.

I've been doing a lot of high way driving over the past few days and my MPG went up from 16.6 to 17.1 at 21 AV MPH. I changed the mode to DTE and it read 96 Miles but then it jumped up to 112??

 

You guys are right about the mph.
I avg between 14-18mpg depending on traffic and how spirited I wanna drive.
As far as the calculation from the pump:

how much gallons of gas you actually put in the car divided into how many miles you drove total till your next fillup.

 

I drive mine with no mercy and pull like 13 on surface streets, but it's really amazing on freeway...like in the 20s...I drive like 60 miles 5 outta 7 days of the week and fill up every 6-7 days...managable if you ask me!