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A little low, but depending on driving style, city vs. highway, engine choice, and how new the car is (MPG increases after engine break-in), temperatures, etc. this isn't outlandish. Where is the 12MPG coming from? I bet that is from the INSTANT MPG display. That is normal, when you step on the gas hard to pass someone, or drive into a headwind, or climb a hill... you should expect that, even single digits. But then going DOWN hill, etc. you will see it go to 40, 50, even 99 MPG.
Is your service engine light on?
[reply] I already said my LaX Super, with its 5.3 V8, got a maximum of 27 MPG on the highway during a recent long-distance trip.
[quote] Wonder if the Chrysler's do better because of the 5 speed auto. trans.?
[reply] The 300C's mileage may also depend on its final gear ratio. I think we can assume that all DICs work the same way. I read where the DIC relies on input from the PCM, which monitors the odometer and fuel consumption rates, and uses it for its MPG calculations.
Anyway, I have copied my post #1263 from the 2010-2011 Buick LaCrosse thread made on 11/19/10. There are quite a few other posts there regarding mileage experiences of 2011 CXSs and CXLs. Here goes:
I probably won't be as complete as bwia but here's my attempt to gauge the gas mileage of my 2011 LaCrosse CXS on a 1600 mile road trip this past week.
My trip was from just south of Portland, OR to San Jose, CA returning to Portland from the Cailf. gold country in the Sierra foothills at Angels Camp. (2 days of great golf in shorts at Greenhorn Creek GC) Starting mileage on car was 624 so I was trying to be careful to not exceed the 68 mph break-in guideline. Typically, I set the cruise control to 67 mph on all freeway stretches. Yeah, it did go over for bursts.
Total miles: 1586 with average gas consumption of 27.177 mpg
I used mid-grade tier one exclusively: Shell, Chevron and 76. I checked and filled my 19" tires to 35# before leaving home. There was very little wind on any of the legs of the trip. Anyone who knows the route on I-5 between OR and CA knows the grades and dips you encounter. Siskiyou summit is ~4500 ft. Then there's Stagecoach Pass, Sexton Pass, Mt. Shasta, the Sunol Grade (2X), etc., etc. Just to give you all a sense of the elevation change challenges in such a trip that defeats great gas mileage that you might get in say, the mid-West.
Speaking of mid-grade gas, the octane for such in Calif. is 89. In OR it is 91. Huh!
The car was stuffed stem to stern. I thought I'd have a challenge getting as much as I wanted into the trunk. But that got filled to the brim and the rear seats were loaded, too. So I was able to take my wife in the passenger seat (creative packing = good move!).
Best leg: Red Bluff, CA to Sunnyvale,CA 222 miles on 7.396 gals. = 30.016 mpg
2nd best leg: Farmington, CA (near Stockton) to Rogue River, OR 386 miles on 13.048 gals. = 29.583 mpg
Worst leg: driving within Silicon Valley,CA 4 days and then to Angels Camp with sightseeing, 288 miles on 12.896 gals. = 22.333 mpg
Overall impression: I'm thrilled! These results far exceed my expectations for highway driving. I received numerous compliments along the way about the styling of the car which went a long way towards helping me see my way to the next car payment. The car is as much a cruiser as any other on the highway - a dream to drive! It handles nimbly (can I say that?) on mountain roads with sharp twists and turns. I love it!
I'm sure I've left out some pertinent details I intended to convey but wanted to post this on the day we returned. If I think of those, I will post them later.
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Here's how those 113 miles were accumulated:
About 46 miles were for a round trip from home to the airport in stop-and-go traffic one way.
The remainder were short trips to stores, etc. of less than 8 or so miles each. Those trips involve getting me back up my hill which is .8 miles of straight up, .4 on a 22% incline. At the bottom of that hill there are a number of ups and downs, too, to get where I am going.
My main point is that while I was very satisfied with my road trip mileage, the in-town driving in our terrain is going to drag my overall experience way down. I knew this would be the case but wanted the CXS for the road trips, primarily. We use our 4 cyl. Equinox for most of the local driving but I just can't resist taking the CXS out every now and again as it's such a pleasure to drive in all other respects.
Truly, YMMV. Happy New Year!
It may have something to do with the accuracy of the pump which is beyond our control.
Hopefully they have found a better way of monitoring.
As to the accuracy of the DIC, I don't understand just how they calculate the fuel usage. It might be the summing of the time the injectors are on and assuming accuracy of pressure regulator. Some regulators vary the fuel pressure with the manifold vacuum and don't have a sensor that measures that vacuum so it would seem they have to use a combination of throttle position and engine RPM to derive the fuel pressure.
I had one such regulator that the diaphram developed a leak to the vacuum line and that was feeding fuel directly into the intake like a carburator system. Other sensors picked up on that as running rich and leaned the injectors. Thus the measured fuel as indicated by the DIC was much less than actually used.
On the Lacrosse, I notice that the car seems to have been designed so that "topping off" is imposssible. When the pump clicks, I can never put in more than say a quart of gas. I don't believe that this "first click" is entirely reliable, but is the "most constant" aspect of the fillup. I always find that the FE is consevative as opposed to "doing the math" with pump gals/trip odo.
I also think that on short trips, the FE indicator "overcompensates" every time you shut down and restart the engine.
They many have added extra protection explaining your experience.
Usually there is some ground slant at pumps and I always pull up so the fill cap is lowest. That is to avoid issues with evap system and also an effort to fill to the same point consistantly.
Granted, some shut-offs are more sensitive than others but they seem to be getting better in that area.
Not sure what you mean by over compensating?
What I have noticed is that when I shut it off, it reads one reading (say 21.3 for argument's sake). When I get back in and start it, it will read 21.1 or 20.9, without ever having moved or idled.
Right now, it reads 18.4. I have approx 200 miles on the trip, and doubt I have used more than 10.5 gals. When I leave work, I shall fill it and see what I get.
27.5 to 30+ on the highway is great for a 4300# car that is heavy (read mass) and safe by all measurements. In town is 16-18 with lots of variables so not consistent
On an all highway run at 72 mph, I have slightly exceeded 30 mpg.
I'm averaging just under 25 mpg with about a 60/40 mix of city/hwy driving and a slightly firm foot on the accelerator.
We wanted a new car with ~30 MPG on our many road trips and the Lacross in either form has delivered for all of us. Great car!
Thanks for the post & good luck. Enjoy the new car.
That is I was expecting better mileage from CXS with 3.6L, simply because of engine improvements.
Maybe pollution standards have impacted.
I was seeing very similar mileage in 96 Olds Aurora with 4.0L V8. Slightly less on my local driving, but hard to beat smoothness of a V8.
And now being in loaner Regal with I4, I'm not impressed with what I see the guages showing me. Less mileage than 09 Malibu with same drive train.
And appears to be about the same as I was getting in 93 Regal with 3.0L and 4 speed auto. That vehicle was checked repeatedly on highway and high speeds would show about 29 MPG. No 24 valves, DOHC, VVT, DI, etc., just SFI, sequential fuel injection.
So, what gives?
I'm averaging about 27 mpg combined city/hwy for my normal driving.
Cruise locked at 60MPH, it was jumping up and down like a yo-yo for the 20 miles I checked. Although still jumping around a bit, it looked to be around 25.8 MPG. On the return run, once I got to the interstate again, I locked at 65 MPH. Again it jumped all over the place and started to settle some past 20 miles. I was in cruise for about 35 miles and the display was showing 32.5 MPG. BS for sure. The only conclusion I could possibly derive is that it possibly get better MPG at 65 MPH than 60 MPH.
And because yours is basic, you won't be having some of the headaches, but watch out for basic issues such as sticking caliper, etc.
Enjoy the car.
And at upper speeds the joggle and sway seems to disappear. That is just great. You have to drive it at speeds of big tickets and gas guzzling to realize some of the features of the vehicle.
I certainly think some dunder-head needs to be removed from the ranks of GM. They must think more power will sell more vehicles with the 2012 change for this engine. It was probably cheaper to squeeze more power than to make it more efficient.
I do have to wonder if some old rules of durability start to come in with the vast difference between 2.4L and 3.6L. Going back just a couple of decades, I4 did not last as long as I6 and that did not last as long as V8. If you were unfortunate to have one of those aluminum I-4 from the days of Chevy Vega, you might make 50K and that was with a lot of oil and dead mosquitoes. (They did use a cast iron block in some and that was quite durable)
What I'm getting at is the final drive ratio. Will the V6 outlast the I4? If we went back a number of years, for some reason Volvo had I4 that would outlast a lot of engines. Yet, today you can even get a V8 in a Volvo when such was not available years ago.
It certainly brings questions of how they will address the now getting close MPG requirements.
I'd heard the big rear wheel drive of Ford is gone. I questioned an officer wondering what they'd do. They apparently have tried some of the Dodges and are not happy with them from dependability and durability perspective. He told me that there are none better than the crown vic, not even a close second. So police are advance buying large quantities of them into storage. I don't understand why, but they want rear wheel drives, he said.
Back when 4 cylinders were only lasting 50K miles, owners of v8's were lucky to go past 100K without needing major engine work. Today's engines are typically the most reliable part of a car, and it is the accessories (AC, auto transmissions, brakes etc.) that break down and and cause so much expense to repair. If an owner changes the oil and keeps his vehicle maintained, this 4 cyl should go 200k easily.
And at highway speeds, the 4cyl is typically turning between 2500 and 3000 rpm's .
I can't answer why you get worse mileage than I do. You should have no problem hitting 25 mpg. Might consult your dealership because you are getting mileage that the 300HP 3.6L engine should achieve.
Congratulations on your new 2012 LaCrosse! I can understand why you may be feeling disappointed about your fuel economy. The EPA's fuel economy estimates are designed to allow consumers to comparison shop, but your fuel economy will almost certainly vary from EPA's fuel economy rating. This is based on a number of factors, such as weather, road conditions, your driving and maintenance habits, and your use of air conditioning.
www.fueleconomy.gov has some great information on how to improve fuel economy (See "Gas Mileage Tips"), and if you decide to get this looked into
by your dealership please be sure to let us know as we're available to assist in any way we can.
Regards,
Sarah
GM Customer Service
Odd, my 2012 PIII V6 get that (or better) on the highway @ 75MPH.
2023 Mercedes EQE 350 4Matic / 2022 Ram 1500 Bighorn, Built to Serve
Congratulations on your new LaCrosse!
Generally, a new vehicle will not achieve it's optimal fuel economy until the engine has broken (this will take 3 to 5 thousand miles). A gradual increase in fuel economy can be expected - please keep us posted on this, though! We're here to answer any questions about the product you may have, assist in the process of working with a dealership, or look into any warranty or recall questions.
Sarah, GM Customer Service