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Administrator, Resident Tater Salad
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If you floor the gas in 6th gear at 1300 RPM - really anywhere below 1900-2000 and you're asking it to go faster, all you're doing is bogging it down and making the engine detonate (yes, it will even on high octane gas if you strain it enough), pull timing, and strain. A modern engine will try to prevent detonation by adjusting the timing but you can still do damage.

By up-shifting at low rpm, you’re asking your motor to deliver power at its point of lowest “mechanical advantage”, which means you’re forcing the pistons, wrist pins, con-rods, crank, and journal bearings to accept the force of a large explosion pushing against a relatively unmovable object.

By all means, downshift for power if you need to go uphill or something and DON'T STRAIN THE ENGINE, just like an automatic transmission would do. Cruising around at low RPM and light throttle pressure is just fine - it will save you gas.
 

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Administrator, Resident Tater Salad
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One thing I noticed today while scanning with Torque is something I had suspected. The car tends to drive itself with regard to throttle position. I'll verify this with a few more scans, but I tested this earlier today while going 45mph in 6th gear. I floored the gas and watched the recorded throttle position in Torque and it didn't go past 51%. If I downshifted and allows RPMs to rise, I would indeed be able to hit higher throttle positions. I wonder if the PCM ignores the fact that you're flooring the gas at very low RPMs in a high gear. Perhaps the engineers thought that if you needed to floor the gas, you should be in a lower gear anyway.
Interesting. Never owned an electronic throttle car before, but that really is pretty smart. The last manual, fuel injected car I owned was a 1985 Saab - give it too much gas in the wrong gear, and it would definitely bog down.

My mom's 2005 Accord manual actually behaves in much the same way, but I'm not sure if that's just the engine's crappy powerband or it really is going to 75-100% throttle when you push on the gas hard. Can't tell with ETM cars, but most I've driven feel like they BOOT the throttle open with just a touch of the gas pedal. My girlfriend's V6 Camry will squeal the tires and take off like a rocket if you even breathe at the gas pedal too hard.
 

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Administrator, Resident Tater Salad
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I had the no-frills, 8V edition of the 900, but drove a turbo and it was a blast. You could definitely lug it in 4th and 5th gears at speeds (35-45 mph on hills). It was the slowest car in the WORLD, but I still loved it. A friend and I timed it in high school, and it took 16.5 seconds to hit 60 mph, foot on the floor. At 323,000 miles, the oil pump died and the engine self-destructed. A sad ending for a car that had served my family faithfully for 21 years.
 

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Administrator, Resident Tater Salad
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Same here. My Volvo lost 3-4 mpg with the AC on, but I notice very little to no difference with the Cruze.


Sent from my Autoguide iPhone app
 

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Administrator, Resident Tater Salad
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I get ~31 in mostly city driving (with some jaunts to 60 mph). 31-32 isn't bad.

My old 2.3 liter engine struggled to get 30 highway.
 

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Administrator, Resident Tater Salad
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well, I filled up this morning, third and probably last tank of 87 octane, I've lost between 10 and 30 miles on thes 87 octane tanks vs. 93 octane. Also, I'm letting my tank get fairly empty til dic reads ~50 miles left, when I used to fill at half a tank, the fuelly numbers were better.
At a difference of 10-30 miles per tank, say you're putting in 11 gallons. If you live where I do, you're paying 30-40 cents more for 93 and 15-20 cents more for 89 octane.

If you're OK with the performance of your car on 87 octane and don't notice the bogging like we do with the manuals, stick with 87. Tank for tank, you're saving yourself about $2.20-$4.50 per tank, while only losing about $1-3 in gas mileage on regular.

It's about a wash, but you're really not *saving* money by running better gas. The car just runs better, which is enough for me to justify the higher octane. You may not be as picky about performance as me, though.
 

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Administrator, Resident Tater Salad
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You have to be running on "empty" for a while in order to put 11 gallons in that tank. It will hit empty when you hit around 10 gallons used. 30-40 cents per gallon more for premium? That's pretty ridiculous. Out here it's 20-25 cents more.
Tell that to my LT's gas tank. I've put 12.5-13 gal in it. Keeps me going to the gas station less though, so I don't complain!
 

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Administrator, Resident Tater Salad
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30-40 cents per gallon more for premium? That's pretty ridiculous. Out here it's 20-25 cents more.
Ugh, tell me about it. This is one picked at random. Even NC where they used to be 10 cents apart per grade has jacked up the price difference between regular and plus and super.

We had regular 30 minutes south of here for $2.97 recently. THAT was awesome.

 

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Administrator, Resident Tater Salad
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I paid $3.12 last fill up on 87. So after everyone telling me to go 93 octane, you now say stay with 87? crazy.
Like I said, do the math. If you are *ONLY* concerned about MPG, yes it seems like in your case, you get slightly higher on premium, but you don't break even on cost using premium for 10-30 extra miles per tank. 30 is just approaching the "break even" point assuming a $.25 cent increase for premium and a 30 mpg average.

Now, if it's about how the car performs like crap on 87 octane, then, by all means, go for the higher octane. The Cruze will run on it - just not as well as it will run on higher octane.

I'm running 87 now, and it runs "ok", but not great on it in the cold temperatures. Summer was a different story. MPG is unchanged for me. I will likely go back to 89 just because I don't like how the car surges at low RPM. Over 1800 though, everything's hunky-dory.
 

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Administrator, Resident Tater Salad
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I am more concerned with mpg, but it sounds like I should maybe try mid grade for the colder months?
Give it a try. I've only run 93 twice since April. I noticed no difference in behavior between the two, and I'm perfectly happy with 89. May give you the MPG increase you're looking for too - I saw ~4 mpg decrease using 87 during the summer in highway driving.
 

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Administrator, Resident Tater Salad
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You don't need to do the intake til around 50K miles/4-5 years or more. That engine is still gonna look almost-new inside right now.

But it would be sucked in through a vacuum line at idle, a little slurp at a time, and not enough to stall the engine. Shut it off, then wait 10-15 minutes and go drive like a hooligan.
 

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Administrator, Resident Tater Salad
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I use cruise control daily on the highway, it helps, but since I drove in manual mode all the time, even though I'm at 1800rpm going 35mph in 6th gear, by the time I'm at 60mph, I'm around 3500 rpm, so I think I can't keep the rpms down much.
3500 at 60 mph? I call shenanigans.
 

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Administrator, Resident Tater Salad
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Yeah, 3500 RPM @ 60 would be like 4th gear on mine. That's a 1:1 ratio. 6th on ANY Cruze is not a 1:1 ratio.
 

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Administrator, Resident Tater Salad
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Hey does anyone know the idle for the 2012 eco mt? Mine idles in the winter at 800-900 rpms. And also, how low can you keep your rpms before it starts to ruin the engine/transmission? For example, xtreme posted that @40mph his rpm's are 1100. I have always felt going that low can be detrimental to the engine/trans. Or is it fine as long as you are above idle?
Keep the RPM where you don't feel the engine shuddering under load. Above 1200 seems to be right for me on level ground.
 

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Administrator, Resident Tater Salad
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89/91/93 octane to increase mileage... Is it actually beneficial? As in, is the extra 2-5MPG worth the extra cost of the fuel?
In my case, no, but I don't like how my car responds on regular in warmer weather.

Regular was $3.17 the other day. Mid-grade was $3.69 and Premium is $3.83. Ridiculous, right? The price gaps are less in other areas, but I usually figure in 50-60 cents/gal for 93 here. If I can get away with it, I just run 89 in all warmer weather but the peak of summer.

In winter, when my car runs fine on 87, I'll take the (maybe?) 2-3 MPG loss and cheaper fuel because it still saves me $. It's up to you to sit down and do the cost calculation...in an area with a 10-20 cent gap between grades, you'll probably save $ running on 89-93.

That said, your driving habits alone are the biggest impact on MPG and $ saved that you'll see at the pump.
 

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Administrator, Resident Tater Salad
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Ok, with that being said, would using 89 (plus) octane fuel be most beneficial for my Cruze, or, should I just stick with using the 87 octane?
I find perfectly acceptable performance in most weather with 89 octane in my car, with no need to jump to 93.

Is that a LS or LT in your sig? Looks like an LS...regardless, try a tank of 89, 93, and 87, and see what your OWN impressions are.
 
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