You do realize that get current accurate readings, you must periodically manually reset the speed/MPG calculator?

 

My car gets 10mpg on average, sometimes worse, sometimes better. As the boost guage goes up the gas guage goes down. Only get about 100 miles on 1/2 tank (10 gallons)....

 

Z has 20 gallon fuel tank. Forget using that worthless mph guage. Fill it up, run it to empty. At next fill up divide miles driven with gallons put in. Also notice you will likely have 2+ gallons left in tank when your DTE says "----" If your NA I guarantee you get more than what you claim.

 

I've driven to Destin, FL from Baton Rouge, LA (about 300 miles) and only burned 2/3 of a tank which averaged out to be around 31MPG. I can imagine getting over 500 miles in a tank if its all highway driving...

In the city I average about 23MPG but I don't exactly drive it like I stole it...

I'm sure my gas mileage will increase a little once my new O2 sensors come in. My car is running pretty rich right now.

edit--
Alberto's right, when the DTE says "----" it will more than likely be between 2-3 gallons left.

 

You crazy mad lead foot man! Kick back and ride [not drive ] in Shawna's from time to time. You are addicted to twins and must ease up. Btw - I will ignore my own advice and PETAL TO THE METAL BABY!

To the OP, as stated by some others, reset your gauge but consider once a month and not at every fill. I use to reset mine on a monthly schedule during the first 4 months of ownership. My average is consistently 22.1MPG and 46MPH in a 2/3 highway and 1/3 light to light driving. I have gotten a little higher MPG when being more gentle with her and shifting into 5th [5AT but always in manual mode] quicker.

There were some threads that describe similar mileage experiences, good and bad, for 6MT and 5AT Zs. It depends on how you drive and in what conditions. I currently rev-up more and shift; hitting the pump more but it's a BLAST.

 

I average about 20-22 mpg, roughly 400 miles on a tank of gas but I drive slower than average, mostly highway, and I skip gears, i.e., shift from second to fourth, third to sixth, etc.

I guess I'll mention the usual cliches, keep your engine in good shape, make sure your tires are inflated and maintained properly, take any excess weight out of your car, and most of all, SLOW DOWN.

 

the best mpg the meter has ever told me was 29mpg from ocean city md to belair md all highway while having a little fun along the way. the worst is definetly around town with a heavy foot coming in at 14mpg ouch!! definetly reset the gauge every time. but to get true mpg you need To follow albertos advice.

 

I don't reset my gauge all of the time and it seems to always settle around 21mpg with mixed driving(spirited, cruising, city/highway) on mostly flat terrain. I can keep it around 26mpg if I try but thats not fun and traffic will eventually provoke me to mash it every now and then.

If you are always coasting down hills in neutral, that will lower your mpg from what it could be.

 

+1

Proper maintenance is essential. My daily Accord V6 has been a symbol of reliability and fuel economy thru 157K and going. Like my Z, she gets all the TLC at every service interval. Pay attention to tire pressure as when low, it affects mileage more than you think .

Don't drive like a mad man. Get to the speed limit quickly and cruise. Highway driving is easier on fuel. But if you are in the city with lots of stop and go, you may in for more times at the pump.

 

Do exactly what Alberto said. I never understood why people relied so heavily on the trip computer. The only GOOD way to know your mileage is to break out those third grade math skills.

 

+1 ROFL

 

That's not to say his gauge is lying to him either... but it's always good to double check. I checked mine a couple times when I first got it and it was pretty accurate.

 

I have been tracking my overall gas mileage since purchasing the car new in March 2006. So far the overall average is about 21.5 mpg. What I don't keep track of (in my excel spreadsheet) is how many of the total miles driven are highway, how many are light to light in the suburbs, how many are city, etc. I would like to know all of that, but I don't spend the time keeping track of those details. Over the course of the 13,600 miles on the odometer (and I bought the car with 13 miles), I would say that my ~21.5 mpg is based on about 1/3 highway miles and 2/3 everything else. Just like everyone else who bought this car, I am not always bashful when it comes to mashing the gas pedal every now and then. For a 300HP engine and a smile always on my face, I think 21.5 is a comfortable number.

Also I think that the MPG gauge is accurate depending on how precisely you need your mpg reading to be. I always calculate it by hand and on the few occasions that I compared my calculation to the computer readout, the two numbers were within about 1 mpg of each other.

Some people mentioned that the computer uses average speed (MPH) as a factor in calculating gas mileage (MPG), but I am having trouble understanding that. Let's say I average about 40 MPH and I always cruise in 3rd gear (i.e. I always start from rest, shift through the gears up to 3rd gear and cruise at 40 MPH), and someone else drives my car and averages 40 MPH always cruising in 4th gear (start from rest, shift through the gears up to 4th gear and cruise at 40 MPH). Obviously I, the person who cruises at 40 MPH in 3rd gear, will achieve less miles to the gallon than the guy cruising in 4th gear at the same vehicle speed because the engine has to turn faster and consequently use more fuel in the lower gear to achieve the same vehicle speed.

So it seems to me that in order for the gas mileage gauge to be accurate it should factor in the vehicle speed and the engine speed to account for cruising at the same speed in different gears. Can anyone give me a more accurate explanation of how it works?

 

I can't see how land speed has anything to do with it. You burn more fuel at 120mph than you do at 40mph, even at the same engine RPM because of increased parasitic drag. Also as mentioned above you can burn more fuel at 40mph depending on which gear you're in... or better yet how much of a load is on the engine. Ultimately what matters is how much fuel is being injected/used vs distance traveled, after all that's exactly what MPG is all about.... vehicle speed is not a function of MILES per GALLON...it just happens to be an additional reading on the gauge for your convenience. If you were to reset your gauge at the top of a hill, and engine brake down the hill until you got a reading, it would show your average speed, but it won't show MPG. Instead it will show "---" because the injectors were closed the entire time and the computer can't divide by zero. Try it..

 

I thought about it some more and I think the issue of 40 mph in 3rd gear vs. 40 mph in 4th gear comes out in the wash...here is how I think the car computer calculates fuel consumption in miles per gallon:

There is some means of recording the fuel consumption rate (i.e. gallons per hour) over a certain period of time, and the computer then averages the car speed (miles per hour) over that same period of time. So then you end up with:

(gallons / hour) x ('x' hours) = total gallons used
(miles / hour) x ('x' hours) = total miles traveled

where 'x' hours is the total time interval elapsed over which the readings are taken

then: total miles traveled / total gallons used = gas mileage (miles per gallon)


So the reason I say that the 3rd vs 4th gear issue comes out in the wash is that the fuel consumption rate (gallons per hour) for the subject period of time at a given land speed will vary depending on which gear the car is in. The fuel consumption rate would be detected via a flow rate sensor somewhere in the fuel system (similar to the mass air flow sensor in the intake) and that information relayed to the computer to perform the calculation.

Look ma', I'ma gittin' an ejumacation!

 

Just set the cruise control to 69MPH.

 

OMG not another MPG thread.

It's 95% HOW YOU DRIVE.

and 4% tire pressure, engine oil, transmission oil, differential oil, air filter, etc.

1% what your mods are (unless you're F/I)

 

Hey Jorge, got any sound/video clips of the new exhaust setup?

 

I average 14.3mpg, sounds to me like you need to drive harder.

 

i get about 12.5 per gallon i have some mods nismo exhaust, r/t high flow cats, injen cai. my average mph is like 15 i dont drive that much in the winter and when i do im pretty much never on the highway. does this seem about right?