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Discussion Starter #1
Well, I know there are a lot of topics on the net about the Terrain/'Nox I4 not getting the MPG that it was rated for.

This weekend we made a family trip down to Nashville from Evansville, IN. Its not a flat route at all and there its nothing but rolling terrain.

I had just recently changed the oil to Pennzoil Platinum to see if would make a difference at all.

On the last trip down there (two weeks ago and weather was literally the same) I set the cruise to 71 MPH and the DIC read 27.9 MPG.

This time I set the cruise at 71 as well and the DIC read 29.3 MPG. The tires were at 37/38 PSI. With a little driving around town and about 60 miles back we stopped at filled up and I hand calculated 26.9 MPG and the DIC read 27.7. The MPH average was 46.9.

I them aired up the tires to 40/41 PSI and slowed down to 66 MPH for the return trip. The car averaged 63.4 MPH. The difference was pretty remarkable to me. The TCM downshifted FAR less and the car just seemed to be in the sweet spot.

The DIC read 33.6 MPG!!!![/color]
Now, ours reads about 1 MPG too high so that is still REALLY **** good. If I had continued at that speed at on flatter ground, I would honestly expect to get 33-34 MPG. By the DIC calculations the range for that tank is right at 600 miles!

I wont have an opportunity to hand calculate as my wife will be doing city driving for the rest of the fill up.

Keep in mind, our vehicle has right over 3k miles on it now. There was NO hyper-milling at all, if I had, I would imagine I could get up to 38 MPG with a few cooperative 18 wheelers.

Take this for what its worth and your mileage may vary! [/color]

EDIT:[/color] Also, forgot to say, we had the A/C set to 67 with recirc ON, so it was drawing a lot off the motor.
 

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Thats great for you but I have never seen any posts on here with that good mileage..I am in Florida and have 5000 miles on my 4I Terrain and the best I ever got was 27MPG..mostly in the average 50 MPH ..Its real flat here in Orlando...I tend to do my own calculations ever other time i go to gas and like i said never saw a 30 something MPG...
 

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I never really had a "concern" since I know that EPA ratings are just estimates based on criteria that may or may not reflect real world driving. You have to consider that this is a huge country with various climates and flat areas, hilly areas, mountainous areas etc..as well as different fuel formulations for different regions. For a vehicle the size and weight of the Equinox/Terrain to get even close to the 32 mpg rating is remarkable when you consider that there are smaller, lighter vehicles with less powerful engines that can't quite make 32 mpg highway either. On my one and only road trip since I got my Nox....I calculated 28.7 mpg which I consider great on a new engine (less than 2k miles) and carrying two people.
 

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Discussion Starter #4
nitti48 said:
Thats great for you but I have never seen any posts on here with that good mileage..I am in Florida and have 5000 miles on my 4I Terrain and the best I ever got was 27MPG..mostly in the average 50 MPH ..Its real flat here in Orlando...I tend to do my own calculations ever other time i go to gas and like i said never saw a 30 something MPG...
Your SLT2 is also, IIRC, almost 200 lbs heavier than our SLE2.

Also, its all in how you drive the vehicle. Like I said, going 66 MPH seems to be the sweet spot to get the EPA mileage. Even a few stops seems to really take down the mileage.

The highway rating is kind of a joke these days as it averages 48 MPH. If it was more lifelike and averaged 60ish then we would be seeing MUCH lower highway ratings.

http://www.fueleconomy.gov/feg/fe_test_schedules.shtml

Remember folks, I have higher than recommended tire pressure, synthetic oil and drove BELOW the actual speed limit. So, if you are going 75 dont expect to get this fuel economy.
 

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Great info, thanks bballr4567!
I'm guessing you have 18" wheels?

For sure, more air in the tires will keep the vehicle rolling further with less gas due to less friction.
Gotta watch out for excess tire wear when over inflating, also less surface area contacting the road so worse handling in adverse conditions.
I believe if you over-inflate the wear will be on the inside of the tread, under-inflate and it will be on the outside of the tread.

Sure sounds like you had her dialed in nice!
 

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Discussion Starter #6
We actually have the 17" wheels.

I will be watching the wear on the tires pretty close. I usually rotate them every 5k miles anyways so hopefully the extra few PSI really wont matter that much.
 

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I have the I4 Terrain w/ AWD and 17" wheels, and ECO on all the time. No oil change yet.

I watch it pretty actively, and at about 11,000KM's on the Odometer, the best I can get on the highway is about 8.2L/100km (28.6mpg), and that's at about 115km/h (71mph). If I slow to about 100-105km/h (60mph), I can stretch that to about 7.9-8L/100km (29.7mpg).

Mixed city/highway (50/50) I get about 9.2-9.4L/100km (25mpg), which is my daily commuting.

I'm reasonably impressed. I'm used to driving small 2 door cars like civics, so it's not quite civic territory (34mpg highway), but it's nowhere near 'big heavy SUV' territory.

Manufacturer's mpg ratings are always under near ideal and perfect conditions, at about 80km/h. Basically, the sweet spot for the transmission and gearing ratios.
 

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Woo Hoo i can't wait to drive my 3000 mile trip at 63mph...not...

I'll take 74mph and 24mpg and live in the real world that GM did not intend...lol
 

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bballr4567 said:
So, if you are going 75 dont expect to get this fuel economy.
Seems to be the same in any car I drive. 65 is really the sweet spot no matter what. I like the highways that have 75 MPH limits, but driving 65 really does change things a lot. I've easily averaged over 34 MPG in our 'Nox at 65.

As far as the MPG test and results, does anyone know where to get the full 5 ratings now done on new vehicles? I still only find the original 2 ratings of city and highway. I'd love to see all 5 tests ratings.
 

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Here's an interesting table...


"Table P-1
Characteristics of 1975 to 2009 GM Marketing Group's Cars "

year test city hwy com lbs vol CID HP 0-60 top hp/CID hp/wt ton-mpg
1975 15.1 11.9 14.4 12.9 4486 343 151 14.0 113 0.450 0.0334 34.1
1976 16.7 13.1 15.8 14.2 4375 329 148 14.0 113 0.461 0.0334 36.5
1977 17.8 14.1 16.7 15.2 4158 113.1 314 145 13.6 114 0.468 0.0346 37.2 2038 4206
1978 19.1 15.0 18.3 16.3 3758 112.2 288 135 13.3 114 0.479 0.0356 36.2 2185 4068
1979 19.3 15.3 18.0 16.4 3726 112.3 283 136 13.1 114 0.495 0.0361 36.2 2205 4076
1980 22.0 17.1 21.2 18.7 3355 109.9 222 113 13.8 110 0.542 0.0337 37.0 2451 4083
1981 23.3 18.0 22.8 19.9 3417 112.4 224 110 14.3 108 0.525 0.0322 39.9 2654 4513
1982 24.4 18.6 24.6 20.9 3327 111.3 209 110 14.1 108 0.560 0.0329 40.9 2776 4583
1983 23.6 17.9 23.8 20.1 3425 114.3 221 117 13.8 110 0.555 0.0339 40.5 2733 4639
1984 24.4 18.5 24.7 20.9 3326 109.5 210 115 13.6 110 0.582 0.0344 40.9 2717 4480
1985 25.6 19.3 26.2 21.9 3299 111.4 207 117 13.4 111 0.594 0.0352 42.4 2899 4730
1986 27.1 20.3 27.7 23.1 3144 109.2 189 115 13.1 112 0.640 0.0363 42.9 3021 4687
1987 27.3 20.2 28.1 23.2 3162 109.8 190 123 12.6 115 0.674 0.0384 43.4 3056 4768
1988 28.2 20.7 28.9 23.9 3137 109.8 179 122 12.5 115 0.709 0.0385 44.4 3149 4884
1989 27.5 20.0 28.3 23.2 3173 110.6 186 133 11.8 119 0.739 0.0415 43.8 3087 4845
1990 27.3 19.7 28.3 23.0 3244 109.8 182 136 11.8 119 0.775 0.0417 44.4 3032 4882
1991 27.2 19.4 28.1 22.9 3236 109.1 187 139 11.6 120 0.774 0.0423 44.1 3009 4821
1992 26.7 18.9 27.7 22.4 3301 110.2 192 146 11.2 122 0.794 0.0438 44.1 2982 4873
1993 27.3 19.3 28.0 22.8 3265 109.9 189 146 11.1 123 0.805 0.0444 44.6 3044 4921
1994 27.5 19.3 27.9 22.9 3276 108.9 185 149 11.2 123 0.824 0.0447 45.1 3038 4921
1995 27.3 19.0 27.9 22.7 3339 111.1 191 165 10.3 129 0.884 0.0488 45.6 3072 5079
1996 27.8 19.3 28.3 23.1 3337 109.9 188 167 10.3 129 0.900 0.0494 46.5 3081 5119
1997 28.1 19.4 28.3 23.2 3308 110.1 183 169 10.2 130 0.927 0.0501 46.5 3113 5121
1998 27.5 18.8 27.6 22.6 3369 111.4 191 174 10.1 131 0.916 0.0509 46.4 3092 5175
1999 27.4 18.7 27.3 22.5 3409 110.7 188 171 10.3 130 0.917 0.0494 46.7 3054 5175
2000 27.6 18.6 27.5 22.6 3441 111.6 189 173 10.3 130 0.921 0.0496 47.5 3096 5309
2001 28.1 18.9 27.8 22.9 3445 111.8 190 177 10.1 132 0.938 0.0508 48.4 3161 5426
2002 28.5 19.1 27.8 23.1 3406 111.4 194 178 9.9 132 0.930 0.0517 48.6 3201 5427
2003 28.4 18.8 27.8 23.0 3490 113.1 192 183 9.8 133 0.965 0.0520 49.5 3223 5617
2004 28.9 19.0 28.4 23.3 3428 112.1 192 183 9.7 134 0.975 0.0529 49.5 3263 5568
2005 28.8 18.8 28.0 23.1 3482 111.9 193 188 9.7 135 0.986 0.0534 50.2 3252 5635
2006 28.3 18.5 27.5 22.7 3584 110.7 201 203 9.3 139 1.027 0.0561 50.8 3160 5654
2007 28.6 18.7 27.7 23.0 3581 108.6 192 197 9.5 137 1.050 0.0547 51.3 3138 5614
2008 28.3 18.5 27.5 22.7 3659 109.5 194 206 9.4 139 1.079 0.0558 51.9 3129 5714
2009 29.1 19.0 28.2 23.3 3666 111.6 196 211 9.3 141 1.099 0.0569 53.8 3303 6012

All I can say is wow. Double the MPG and yet double the HP per engine size over the years.
 

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Do we know if that table calculated adjusted for the new government standards dictating how MPG should be calculated?

That is pretty amazing info... thanks for posting it!
 

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gearhead said:
Gotta watch out for excess tire wear when over inflating, also less surface area contacting the road so worse handling in adverse conditions.
As long as you don't exceed the max cold pressure stamped on the sidewall you really aren't over inflating the tire. An internet search will reveal more information than I'd care to absorb about tire pressure vs driving conditions such as speed, loading, road conditions, and so forth.

I've always considered the recommended pressure as a minimum and the sidewall number as a maximum and adjust the pressure according to what I'm doing. I usually end up with a good compromise between fuel economy and ride comfort somewhere between those two numbers.

As a side note...there's a reason airplane tires use pressures like 200psi. The speed (in knots) at which a tire will begin to hydroplane is 8.6 times the square root of the tire pressure...give or take a few knots.
 

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bballr4567 said:
Its not a flat route at all and there its nothing but rolling terrain.
I'm jealous. I'm still doing the breakin on mine and am using a relatively low speed route with a lot of hills and am struggling to break the 26mpg barrier.

I did notice that I could do a little better in manual limiting the tranny to the first 5 gears. It doesn't seem to have enough torque in 6th gear and lugs down, shifts, lugs down some more, and shifts again...all of which seem to hurt the mileage. Running in 5th gear results in less shifting, closer speed to what is set on the cruise control, and a couple more miles per gallon.
 

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Discussion Starter #14
If you are still breaking it in, dont worry about MPG. You will just not give the engine the RPMs it needs to properly seat the piston rings. Whats worse, is that you have lugged the engine. Not good at all. We took it easy with our last Ecotec in our Malibu and it rewarded us with piss poor MPG for the whole year and 24k miles we had it.

Trust me, we drove ours HARD for the first 750 miles and its still been getting better and better each fill up.
 

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bballr4567 said:
If you are still breaking it in, dont worry about MPG. You will just not give the engine the RPMs it needs to properly seat the piston rings. Whats worse, is that you have lugged the engine. Not good at all. We took it easy with our last Ecotec in our Malibu and it rewarded us with piss poor MPG for the whole year and 24k miles we had it.

Trust me, we drove ours HARD for the first 750 miles and its still been getting better and better each fill up.
Driving it "hard" isn't the answer either. I have a friend who is in the "drive it like you stole it" camp when it comes to breaking in new engines and his cars don't have the compression, horsepower, and fuel mileage that mine achieve. To properly break in a new engine you have to methodically use the entire rpm range.

The way I do it is to warm it up by driving at varied rpms for about 10 miles or so then do 4 or 5 "vacuum pulls" by slowly accelerating to redline and letting the engine coast back down to idle while in gear. Then I drive for several more miles varying the rpm and repeat the vacuum pulls, I then drive for a few miles at varying rpms and park it overnight.

I repeat that process 3 times then just pretty much drive it normally after that as the rings will be pretty much taken care of. The rings are only one thing that needs to be broke in and although they are probably the most important my ritual doesn't really take care of the bearings and other stuff so it will be a few thousand miles before all is as it should be...but normal driving will take care of everything else.

If you REALLY want crappy mileage just drive your new car in rush hour traffic (low rpm mostly idling) for the first several hundred miles. There's nothing you can do short of rehoning the cylinders and replacing the rings if you miss the window of opportunity to properly break in the rings. And if you "baby" the engine for several thousand miles the first time you gouge on it and it hits redline it will probably break a ring or two.
 

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Discussion Starter #16
I said I drove it hard, not like I stole it. To me that is two different things. We used the whole RPM band once warmed up at least once per start. Nothing more to it than that.


Anyways, back to the fuel mileage. Just got down to FL from IN and for the WHOLE trip we are averaging right at 28.5 MPGs. That is with some driving around in Nashville to see my wifes parents but yea. Average speed has been around 75-77 so needless to say, VERY happy with the results.
 

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Discussion Starter #17
Well, we finished the trip yesterday. The Terrain performed beautifully. The only issue I have is with the cruise and I hope I can talk to a GM engineer about the issue. It really makes driving in hilly, even a small hilly environment, annoying.

I will update this later on tonight when I get all the fuel slips.
 

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bballr4567 said:
Well, we finished the trip yesterday. The Terrain performed beautifully. The only issue I have is with the cruise and I hope I can talk to a GM engineer about the issue. It really makes driving in hilly, even a small hilly environment, annoying.

I will update this later on tonight when I get all the fuel slips.
Good luck on that one....

Engines lack any torque down low, they are going to downshift, and being its a 6spd, many times that downshift is going to 4th the rpms up to the powerband. 1 reason even though I perfer the 3.0 to the 2.4, I wish GM would've used its current engines vs create new ones. I still say the LNF should've been the upgraded engine for this car, 260 torque under 3k would've been perfect for the Nox (plus 290hp/315torque factory stage kit ;D).....but people would think 2.0L...WTF do they smoke

and whats really funny...I would beat the LNF would've had better fuel ratings then the 2.4 setup :) if equally geared
 

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Discussion Starter #19
The downshifting is expected, however a downshift to 4th from 6th is unneeded 99% of the time. During the mountain climbs, I would manually put the car in 5th and had PLENTY of power to climb at 75 MPH.

I always keep the INT MPG figure up to see how Im driving and going up the MTN usually returned a 19-20 MPG in 5th. If it downshifted to 4th, it would drop to 10-11.

There really wasnt a need for it to go to 4th/4300RPM when 5th/3200RPM gave plenty of power. Its fairly easy to modulate the throttle to keep it in 5th for the unwanted downshift and that is how drove for the majority of the trip.
 

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bballr4567 said:
The downshifting is expected, however a downshift to 4th from 6th is unneeded 99% of the time. During the mountain climbs, I would manually put the car in 5th and had PLENTY of power to climb at 75 MPH.

I always keep the INT MPG figure up to see how Im driving and going up the MTN usually returned a 19-20 MPG in 5th. If it downshifted to 4th, it would drop to 10-11.

There really wasnt a need for it to go to 4th/4300RPM when 5th/3200RPM gave plenty of power. Its fairly easy to modulate the throttle to keep it in 5th for the unwanted downshift and that is how drove for the majority of the trip.
I find the tranny programming lacks any logic behind it....and would overall improve the "reviews" of the cars if GM would get off there rears and fix it. Lazy to get into gear, lazy to shift, always wants to put it in the highest gear as soon as possible (when its not needed), when it feels the first bit of "strain" on the engine downshifts like crazy (hitting a luvbug causes downsifts!).....Then do not even get me started on the feeling of "drag" these latest transmissions have....The 6T70 isnt nearly as bad as the 6T45, let off the gas and its like applying the brakes!
 
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