[Atomic]

Hey all,

I just recently picked up a used '11 LT auto with 12k miles, and have seen quite a few threads on the poor FE being had with this particular setup.

I've gone through my first tank, and saw 36.8mpg with an approximate 80/20 HW/City split. I was expecting low 30's in a best case scenario. What I've determined is either people are exaggerating their light-footed driving habits/speeds, or I got lucky.

My highway miles were done on relatively flat interstate with a few rolling hills at 68-73MPH. City was mostly heavily congested stop and go.

TL;DR = reading these forums had me planning on poor MPG, but everything seems much better than expected :th_dblthumb2:

 

[cwerdna]

Is this based on the DIC or manual calculations? In your case, your tires and car are more broken in than some folks w/new ones. Also, the tires are more worn. New tires can appear to yield lower mileage than ones w/wear for a # of reasons (Tire Tech Information - Tire Rolling Resistance Part 3: Changes to Expect When Switching from Worn-Out to New Tires).

Besides those people possibly "exaggerating their light-footed driving habits/speeds", there are so many other factors such as trip length, % of highway vs. city, alignment, tire pressure, habits, habits, etc. that I really think someone needs to take ownership of a standard questionnaire that complainers are required to answer, like the one I proposed at http://www.cruzetalk.com/forum/27-f...fuel-economy-complainers-required-answer.html.

 

[GoldenRS]

We've been happy overall with our gas mileage on our LTZ RS at almost 8700miles. My wife is the primary driver doing 90/10% city/highway driving. She's been averaging 23 throughout the summer in the city and 33 when we've taking it out on long trips of over 50miles. With cooler weather now in place, she's been averaging 21 in the city.

We recently went to northern Minnesota along the Lake Superior shore. We averaged 32mpg round trip with 4 people and the trunk was full at an average speed of 75mph. Okay by my book..

Before we had our Cruze , we owned a 2007 Saturn Aura XR with all the bells and whistles with the 3.6 that would get about 17city/27highway(summer) & 14city/24highway(winter).

My friend who's kids are big into sports drives a 2005 Ford Excursion 4x4 w/the 6.8 v-10 and that averages about 10mpg in the city & 14mpg on the highway with that nice 44gal. fuel tank. But that can haul a small village inside..

ccasion14:

 

[ErikBEggs]

I just got back from Baltimore. Was a 60 mile trip each way. Going down I was alone, just me and a suitcase. 70 mph CC. DIC gave me 34.5 MPG.

Coming back with 4 people in the car, a full trunk, no cruise control but my FE trained right foot on those maryland hills between 65-75 mph gave me... 37.6 MPG on the DIC. If I extrapolated a longer trip to a full tank of that, based off my history with the DIC vs. manual, that equates to 36 MPG manually calculated give or take 0.5 MPG. I cannot complain. Of course, I have to revive my thread now because when I was tuned, that same kind of driving style was barely giving me 32 MPG.

I've gone through my first tank, and saw 36.8mpg with an approximate 80/20 HW/City split. I was expecting low 30's in a best case scenario. What I've determined is either people are exaggerating their light-footed driving habits/speeds, or I got lucky.

If you are pure stock, than yes they are exaggerating. If you keep it 55-65 mph on your urban highway commute, 36.8 MPG on 80% highway is definitely obtainable. The only place for me when this car gets in trouble is on the open road when your speeds start creeping above 65 mph. 70ish is usually ok especially because you have to keep up with traffic, but when you start hitting 75 mph your right to complain is revoked .

 

[70AARCUDA]

DEVIL'S ADVOCATE STATEMENT--a momentary MPG-value displayed on the DIC does NOT mean that's the MPG value for the whole trip; it's only the value for that SINGLE value displayed. The MPG-value for the whole trip is a "time-averaged" value of every HIGH and LOW MPG-value that was displayed on the DIC, NOT just the one, single, "high-water-mark" value! Moreover, the DIC seems to over-estimate its MPG numbers.

 

[ErikBEggs]

I'm assuming the OP used the manual calculation method.

DIC we know is just a rough estimate. But if your DIC is saying 37 MPG over 50 something miles, you aren't getting any worse than 34-35 MPG hand calculated if you were to finish out that tank, as that is a 5-10% margin of error. Mine has never been that inaccurate. And it's actually MORE accurate I've noticed on highway trips for me personally. The city with all the stop and go accelerations is where it undercuts gas consumption noticeably.

 

[Atomic]

To answer the question, my reading was found using manual calculation. Even though the DIC was only off by ~1.5mpg, I still won't ever rely on it for a pinpoint reading. I'll be curious to see what I can pull off when I make a 425 mile trip home to northwestern Illinois over Thanksgiving. Given that it is mostly flat interstate driving, I can probably pull off nearly 40 as long as I'm not driving into hurricane strength winds.

On my last trip home in my Camaro I managed an incredible 33.5mpg driving between 75-80mph. Full exhaust and CAI certainly have a large part in that. I am curious to see what sort of FE increase I would see with an intake on the Cruze...

 

[ErikBEggs]

What kinda RPMs was your Camaro spinning at that speed? It must have a TALL final gear, which really makes a car exceed EPA.

 

[Atomic]

What kinda RPMs was your Camaro spinning at that speed? It must have a TALL final gear, which really makes a car exceed EPA.

Indeed it does. It has the 4-speed auto with 3.08's and sits around 2300-2400rpm at those speeds. I consistently get over 30mpg in ~100% highway trips, and the combination of gearing, aerodynamics, and modifications to help the efficiency of the motor (full intake/exhaust) has certainly paid for itself many times over.

About 4 years back I blew the transmission when I was 250 miles from home. I had lost 1st and 4th gears, and drove it home in 3rd gear at 4000rpm lol. Engine in that car is indestructible.

Back the the Cruze, however... I have read many threads outlining the performance gains to be seen with the intakes we have available, but I can't seem to find anything on it's effect on the FE. I know there isn't 5+ mpg to be gained, but I know I saw roughly 2mpg increase when I put the CAI on my Camaro. Similar gains would certainly be appreciated.