i wasted more calories thinking about this than I would gas if I didnt.

nonetheless, I have reached a conclusion


the more you drive your g, the more fuel you waste

therefore, get to point B as fast as you can

 

60mph in 6th gear at 2k rpm vs. 60mph in 3rd at 4700rpm uses the same fuel and the same air. It simply does not take much fuel to maintain 60mph, regardless of gear (ok maybe not 2nd gear). Press the gas pedal and now you will start to use more fuel. Floor it, and the engine will receive the max fuel/air it can burn, determined by the ECU given data fed to it by lots of sensors. In 6th gear, that is probably going to be a smaller amount than in 4th, in this scenario, but then 4th will send you accelerating aggressively ahead while 6th will just barely speed up.

Your statement is ony true for FI engines which the vast majority of us don't have. For non-FI engines the amount of gas going into each cylinder is approximately the same regardless of engine rpm. The reason that you get more acceleration when you stomp down on the gas pedal is not because more fuel is going into the cylinder, but because the engine rpms dramatically increase.

You suggest that gas mileage is determined by car speed and not engine rpm, but then you back track by saying maybe not 2nd gear and I'll add definately not first gear. The only advantage of going 60 MPH in third gear rather than 6th gear is that the lower gearing gives you a mechanical advantage thereby enabling you to accelerate faster than if you were in 6th gear.

For those of you who believe otherwise simply never shift into any gear higher than 3rd and watch what happens to your MPG. I wouldn't advise doing this for a prolonged period of time because other than killing your gas mileage, the wear and tear on your engine will be increased substantially.

 

^^^ yea, I noticed that also

navi gas monitor always says the same thing at 60mph even when I am in 3rd gear. thats why I believe it. Honestly, we have so many sensors looking after us, its best not to worry about it

 

Why are you people making this harder than it seriously is? Its a simple theory.

Low rpm = less work, less air, less fuel, better MPG
High rpm = more work, more air, more fuel, worse MPG

I wonder why it is that everytime I redline 1st, chirp 2nd, redline 2nd, chirp 3rd, I can see the gas gauge needle go down 1 notch...hmmm

People man...

 

i hate chilibowls

 

OK. Then never shift into any gea rhigher than 3rd. The only accurate way of measuring fuel consumption is to fill your gas tank, set your trip odometer to zero, and then divide the miles driven by the number of gallons added at your next fillup. Anything else is just an estimate.

 

I agree. It's not at all complicated and you are right on target. The best way of improving your car's gas mileage is to accelerate quickly out of the lower gears into the higher gears. If 3rd gear would yield the best gas mileage, then auto manufacturers have been wasting money for decades by adding an overdrive gear in their auto trannies.

Higher RPM = bad gas mileage
Lower RPM = good gas mileage when in higher gears

 

all my shifts are in between 2k and 2.5k my nav says i got 22.1 mpg, one time i measured by dividing the number of gallons with the amount of miles and my nav was off by about .2 so yes the nav is jus an estimatation but its not off by much secondly my cousin drives his z and all his shifts are between 2.5k and 3.5k and he gets about 17mpg. thats what his little reader thing tells him. so in conclusion the higher the rpm's the less gas mileage, back to the original question though i think if you have a 6mt their is a shift pattern also that saves gas
i think it was
skip 1st gear
start in second and bring it to 3k rpm's
third to 3k rpm's
skip 4th
5th to 2k to 2.5 rpms
and jus shift into 6th and accelerate gently.
when you shift into 6th gear you should be around 40 to 45 mph
i dont know if it works because i never practiced it on a whole tank of gas but next fill up this might be my experiment, one of the tech's at infiniti told me this pattern

 

That is really going to extremes. Starting out in 2nd will take a lot more life out of the clutch, since you have to feather it a lot more, since the take off is much longer. Secondly skipping gears to this extreme will take most of the pleasure of driving experience out, which concludes you spent this much money on a nice sporty car, not because of performance but looks alone, which means you are a girl. Don't take this to heart.
I save on gas by shifting early, when I'm in traffic or other such reason, but when I safely can, I sure enjoy this car. Let the car eat as much as it needs.

 

hahahaah thats funny i dont drive like that, i just said thats what one of the tech's at infinti told me, but i do start out in second sometimes though and im pretty good at it by not staying on the clutch too long, my neighbor with a c6 zo6 starts out in 6th gear all the time and he has been doing it for almost a year now, so i see no problem with starting out in second

 

If you have an automatic, drive it in auto mode. The car's computer shifts for maximum fuel efficiency, as it is always in "overdrive" like all Nissans that I know of. That's why you're in 5th gear already at 40 mph when in automatic. The engine is keeping your RPM's low because that's what's efficient. It's also a very smart ECU in our G's...even in automatic, if you're in 5th gear and you floor it, it will downshift for you and you can watch your RPM's go through the roof as you take off.

RPMs = Revolutions Per Minute
What causes those revolutions? Fuel combustion. The engine doesn't move on it's own - it takes fuel. At higher RPMs, the pistons are moving faster because more fuel is being combusted. No one here (with half a brain) will argue with this point. If you accept this fact, then logically, what follows is what the last few folks have been saying ---> High RPMs = higher fuel consumption/lower gas mileage
Low RPMs = lower fuel consumption

 

OK! time to talk some logic into my friend about this!

 

I just wanted to post this because I finally saw where I had read it, trey.hutcheson posted it again in another thread today:

From page EC-25 of the FSM:

Quote:
FUEL SHUT-OFF
Fuel to each cylinder is cut off during deceleration, operation of the engine at excessively high speeds or operation
of the vehicle at excessively high speeds.


From page EC-26 of the FSM:

Quote:
SYSTEM DESCRIPTION
If the engine speed is above 1,800 rpm under no load (for example, the shift position is neutral and engine
speed is over 1,800 rpm) fuel will be cut off after some time. The exact time when the fuel is cut off varies
based on engine speed.
Fuel cut will be operated until the engine speed reaches 1,500 rpm, then fuel cut will be cancelled.

 

Stomping the gas pedal does not feed more fuel into the engine? Seriously? I could have sworn the throttle body opened up, allowing more air in, and the ECU responds by injecting more fuel in, according the A/F map in the computer? I thot the engine RPMS dramatically increase when you stomp the gas BECAUSE there's more fuel being taken in....

I'm really starting to believe you guys maybe I'm totally smoking crack? I never tried to claim that you should drive around in 3rd all the time. What I was saying is that the difference is not major, and thus, if you feel like waiting a few extra seconds to shift up, you're not going to see a huge change in your MPG. And the reason I said "except for 2nd gear" is because I've acknowledged all along that with very high revs you see much worse efficiency for lots of reasons (parasitic drag, a/f ratio, etc)

 

You've got the cause and effect reversed. The engine takes in more air, and therefore more fuel, only because the RPM's are rising. The throttle isn't there to cause the increase in RPM's, but to prevent it - the natural tendency of an engine is to rev till it can't rev any more.
It's not like the engine can take a "deep breath". The air is drawn by vacuum into cylinders of fixed displacement. No matter where the engine is in the power band, the air charge is the same, and the A/F ratio is relatively constant. The cylinders themselves don't work "extra hard" when you stomp the pedal, they just cycle faster.
Granted, there's some optimization coming from valve and spark timing, A/F ratio, etc., but that's really just window dressing on the basic principle.