I'm not sure if this is true for the g35, but alot of cars go into a closed loop mode during WOT, which means it runs off a preset fueling/ignition map which usually is rich for engine safety, so while in theory you would be doing the same amount of work in a perfect engine, this is likely not the case in the real world. At WOT you dump in more fuel than is necessary for combustion, which would increase gas consumption. Not sure if this pertains to the g35, but it does to alot of cars, so it is something to take into consideration.

 

Floor it off the line every time... and see what kinda gas milage you get.

This is a no brainer question.. driving like grandma will yield the best gas milage...

Why do you think they lowerd the speed limits to 55 back in the day.. cause most cars will get the best milage at top gear that speed.

My dads Dodge Ram 3500 Dually got 18 mpg at 70 on the highway.. go up to 75 and it dropped to 15, go 80 and it dropped to 11.. cause your engine is working that much harder to push the truck or car through wind resistance.

 

i too heard of this alternate air/fuel map at wot, but can't find anymore info on here.......anyone with specifics please chime in!!

 

the old Deisels work differently than gas engines. They inject a pre-metered amount of fuel per combustion cycle no matter how much air is drawn in.

It's actually really cool, on the big rig engines there is basically a little 6 cyl engine thats belt driven. It draws in fuel and then squirts in into the engine cyl. It has a little crank and everything.

So, it's fuel consumption is based on RPM not on load.

 

if number 2 was true, people doing a 1/4 mile drag, would get really good gas mileage, and be able to do about (20 gallons to 16 mpg... let's see, carry the one... 320 miles... times 4...) 1280 1/4 mile runs in a day...

now they can't because of the reasons everyone else has stated.

 

I actually read a study about acceleration and gas mileage, and the answer is somewhere in between 1 and 2.

Effectively, when get into the 4-6K rpm range frictional losses rob too much power. However, WOT also is inefficient for fuel usage. I believe the best overall fuel mileage they recorded was a half-to-two-thirds acceleration through about 2500-3000rpm and then shifting. This gave them more acceleration for the fuel, but avoided most frictional losses.

The "exact" shift point is, of course, open to debate since each engine and road differs. But a heavier foot on the throttle but a short shift'll get you there with the least fuel.

Luck,


Rick

 

I can't speak with authority as to how the navi integrated real-time mpg indicator gets it's data. however, from my observations it appears that it is measuring fuel flow with good accuracy.

If we can assume that it is an accurate indicator, I would say that the G35 does not appear to burn extra fuel at WOT compared to just under WOT. I will also say that the reason that you can't floor it to redline every time and get good mileage in practice is that doing that will require you to brake when you encounter traffic... and then re-accelerate when you are clear off traffic. That energy loss in braking costs you the MPG.

what I'm saying is if you perform the same work... ie move the car from point a to point b (NO BRAKES, let's keep it simple) in the same amount of time, you'll consume about the same fuel (yes i think there will be a small difference due to extra friction at high rpms) in doing so whether you go WOT to 60mph and then cruise or you granny it but then need to cruise at 78mph to get there in the same amount of time.

So the granny shifting isn't really more fuel efficient in and of itself.. it is a different driving habit that's more fuel efficient.. most people who granny shift will not then cruise a higher speed to make up the difference... they just decide it's ok to take a little longer to arrive at their destination (and have a lot less fun hehe).

Traveling slow, in general, is more fuel efficient. Traveling faster (whether by fast accel then longer cruise or slow accel and higher speed cruise) is less fuel efficient. Traveling up a hill... ie, doing more work, is less efficient than traveling down a hill.

Here's a good question... how much more fuel do you burn by cruising in 4th gear at a constant 60mph on a flat surface vs. 6th gear same conditions?

 

with method 1, and to get better gas mileage would work best if you coast whenever possible. I've tried many different ways to get most out of each tank and found that taking out of gear and coasting will raise the MPG. At some point, the computer will not register the miles till empty cause I managed to beat the estimated miles till empty.
Light on the gas pedal all the time when driving, upshift at 3K RPMs, coasting most of the time on freeway.

 

Well I've seen a lot of guys and gals on here talking about getting 15-18mpg while "driving it like they stole it", whereas I drive like I can't afford $3.09 for a gallon of gas and my computer tells me I get almost 22mpg mixed use with some excessive acceleration. The less use use the gas pedal, the less you use your gas.

 

That's the difference between open loop (WOT) and closed loop (engine adjusts fuel based on input from the O2 sensor, TPS sensor, temp sensor, etc.). All fuel injected vehicles now do this AFAIK.

Curt