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personal experience... 2900-3100 is what i always cruise at gives me the best gas mileagefor the speeds i drive in which is around 120km/h. just try to stay outve boost
 

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The lower the better...
 

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I shift at 2.5k and cruise on the highway at 65mph (speed limit here is 55 anyway lol). I'm averaging 24-27 mpg.

Not that mpg even matters :wiggles:
 

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But past a certain point the engine can't make enough torque to be efficient, so what point is that?
I didn't say to lug it, I suggested to keep the RPMs as low as practically possible to get where you are going, and you will get the best MPG that you can that way...
 

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I shift at 3,000, and then into 5th at 50mph unless going uphill, then I wait 'til 55 mph. I have been getting 28.5mpg with 50/50 city/hiway, so it seems to be working pretty well on my '09. I do romp on it several times a day, up on-ramps and to get by the occasional ****head, just to keep everything in working order !
 

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As low as possible is correct.

There's basically a BSFC - an (almost) linear correlation between the BHP output of your engine and the fuel consumption, for certain ranges (think CL). To go a certain speed, you need a certain amount of torque. Since torque * rpm * (arbitrary constant) = HP, the lower your RPM for that particular torque, the better.

The situation only gets worse - higher speeds get exponentially worse in terms of wind drag (increasing torque required), and higher engine speeds could start dragging you into OL fueling, and could definitely target richer cells on your fueling map.

Basically, keep it below 70 in 5th gear (with the ratios I'm used to), and if the next highest gear will let you sit around ~2k or above, shift.
 

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How hard you're pressing the gas matter more than your RPM. Hammering on the pedal at 2k RPM will burn a lot more fuel than coasting at 5k RPM.

I've done a lot of comparisons in different cars and regardless of the car/engine type RPM matters much less than how hard you hit the throttle.

Along the same lines, turbos burn gas much more quickly at high RPM than naturally aspirated motors, so staying out of boost also saves gas. You can stay out of boost by staying at low RPM or by simply not hitting the gas hard.

And of course the faster the engine turns the more gas it burns versus lower RPM, but throttle pressure plays much more into the mileage as stated above.
 

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I shift just above 2k around town. I average 24+ mpg city all day. On the freeway, I suggest keeping it right at the speed limit, if not lower if you want the best mpg, that's pretty much common sense.
 

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You are better off (for higher MPG) in a gear that makes the engine work a bit at a lower RPM (not lugging the engine), than higher RPMs, almost always...
 

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^this.. load and throttle opening angle are far greater contributing factors to mpg than rpm.
load clearly - I mean, that's just a few multiplications away from being injector duty cycle :p

And no, is the cruising type situation I'm talking about (same speed, same conditions, going one constant speed, or for a particular amount of torque required), the 2k situation will, 100% of the time, be better on gas than the 5k situation, even if you're talking a steep uphill which requires WOT at 2k.

Now acceleration is a different matter altogether.
 

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..even if you're talking a steep uphill which requires WOT at 2k.

Now acceleration is a different matter altogether.


That's contradictory.. because driving up an incline is accelerating in a sense, even if RPMs are kept constant. I have the feeling WOT at 2k RPM is going to consume much more fuel than 7% throttle opening angle at 5k RPM.. when I get my car back I can test it and post graphs of IDC to see.


Think about the Top gear episode where they proved a Prius gets worse mpg than a M3 driving at the same pace..
 

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The problem I have with that top gear episode is that they're fundamentally different cars, with completely different everything.

I'd really like to see that test done, actually - I may figure out a way to do it myself.

BTW, making sure I'm clear on this - the IDC for the 5k situation would be lower than the 2k situation, but has to be multiplied by 5/2, since there are 5/2 times as many injector firing events, right?
 

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I have been watching my ScanGauge and how my gas mileage if effected by how I drive for the last 7+ years, and without fail I ALWAYS get better MPG when I shift early and keep the RPMs down... Now I'm sure there are "some" situations that higher RPMs may work out just a little better but generally not...
 
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