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Hi. Mine's a 2 litre diesel auto in the euro 2010 model.

I'm getting a steady 43.3mp(UK)g with the aircon off over a 2 hour commute which is mostly motorway (freeway) but has some 25 miles of local main roads in total at the ends. If I put the aircon on, I lose 2mpg.

I mention that it's UK gallons because they're bigger than US ones... which brings me onto my next enquiry:

How come you guys are getting so much better figures than I, when most of you are using the smaller US gallon? Is it simply because there are fewer changes of speed on your commutes and your accelerator stays in the same position more of the way there? Or is there something about the US engines which is different?
 

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The US engine and drive train are different from the European and Australian diesel Cruze.
 

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Discussion Starter · #5 ·
No way for me to know whether that figure is accurate but they're presenting it as a conversion, as if the relationship was fixed...?
 

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If you can raise the temperature of 1,000 pounds of pure water at sea level 166.781*F with one gallon of diesel fuel with 100% efficiency, you know you are getting 166,781 BTU's of heat energy.

Ha, don't try this at home.

Do you have cut rate fuel stations there? Sure makes a difference where I buy my fuel in Central Wisconsin.
 

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My commute is 94 miles one way. It starts at 4:15 am, with very little traffic. The route goes through relatively hilly eastern Kentucky with little true flat roads. It is almost the perfect route, minus the hills, with only three left hand turns (Left hand turns usually require a full stop before crossing oncoming traffic) and only two stop lights that are typically green early in the morning. Typically only one or two complete stops on the way to work makes for a lot of time in overdrive at low fuel consumption levels. The cruise control is almost always used and set to 59 or 71 mph depending on the speed limit. My car/commute doesn’t yield drastically high numbers as some guys are seeing. The fuel economy on my car stays fairly consistent in the mid 50 mpg range.
 

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Starts and stops and going fast will kill the mileage really quick. I have t taken mine on a trip since I deleted it. The +1000 mile trips before have yeilded record segment numbers on the DIC, but overall I think the avg is about 42. I'm in the middle of Texas and we have plenty of raids where the speed limit is 80 so I'm going to drive at least that. At that speed the instant MPG my climb to 45 but any rise will drop it into the 30's. 10mph makes a big difference on a 1000 mile trip and a few mpg's are not worth the time they cost me.

If you want to make the effort to do the hyper mile commute you have to work at it. I can pretty easily get 5mpg better than my wife in The Cruze, my daily driver is an F250 with a gas V10, I've learned to work it to stay above 10mpg and the tricks I do without thinking to get an extra 1/10th make pretty big gains with the Cruze.
 

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Hi. Mine's a 2 litre diesel auto in the euro 2010 model.

I'm getting a steady 43.3mp(UK)g with the aircon off over a 2 hour commute which is mostly motorway (freeway) but has some 25 miles of local main roads in total at the ends. If I put the aircon on, I lose 2mpg.

I mention that it's UK gallons because they're bigger than US ones... which brings me onto my next enquiry:

How come you guys are getting so much better figures than I, when most of you are using the smaller US gallon? Is it simply because there are fewer changes of speed on your commutes and your accelerator stays in the same position more of the way there? Or is there something about the US engines which is different?
does your car have LRR tires, shutters, underbody panels?
 

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Discussion Starter · #11 ·
I don't know what any of those things are... :(
 

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Our gen 1 diesel is a mix.
We have the bolt-on under body panels from the Cruze eco, the suspension and better brakes from the RS.
Then we have our own tires and low rolling resistance (LRR) tires.

I get an average of 40 to 43mpg over the course of a tank with 25mile average economy highs of up to 55mpg depending on the weather. Mostly down hill with tail wind and drafting trucks gives nice mpg numbers on the highway.
 

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Tom,

LRR - low rolling resistance fuel efficient tires. You can get those in the UK.

Shutters - to decrease airflow through the radiator, there are shutters that open/close based upon speed and engine load. This decreases 'cooling drag' that results from air flowing through the engine compartment. It's a real thing! This is now being incorporated in newer engine cowlings for small piston airplanes and results in significant speed increase (or economy if the pilot throttles back).

Underbody panels - there are panels attached to the underbody to smooth airflow and decrease drag.

The North American cars also have a deeper chin spoiler to decrease air flowing under the car as well as automatic transmissions that are presumably tuned for efficiency.

That being said, the tremendous fuel efficiency numbers that people are posting are probably not representative of the entire fleet of diesel Cruzes. If the car is driven in any situation that requires continuous changes in gas pedal setting, then the car's efficiency goes away.
 

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That being said, the tremendous fuel efficiency numbers that people are posting are probably not representative of the entire fleet of diesel Cruzes. If the car is driven in any situation that requires continuous changes in gas pedal setting, then the car's efficiency goes away.
Definitely true. There is a definite bump to instant MPG's when I switch to cruise control.
 

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2014 Gen 1 Cruze Diesel (US version)...to achieve 50-55 mpg, I have to keep the cruise control set for 60 mph, hope for favorable winds and NO stopping.

Driving with normal traffic flows (70 mph) and a few stops, fuel consumption drops to about 46-47 mpg.

Around town driving kills fuel efficiency, usually in the mid to low 30's mpg.
 
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No way for me to know whether that figure is accurate but they're presenting it as a conversion, as if the relationship was fixed...?
Not fixed, as in a physical law or relationship. The amount of heat energy (heat of combustion) in a gallon of gasoline varies depending on the composition, which depends on the crude source, the processing, and the (re-)formulation. Not sure how much this is also true of diesel, but I am confident it is true to some degree. Also, since liquids & moreso organic liquids expand & contract quite a lot as the temperature rises & falls, it is more exact to give energy content per unit mass, rather than per unit volume.

This might be interesting: https://en.wikipedia.org/wiki/Heat_of_combustion . You can convert weights to UK gallons, etc., etc., then maybe match Stonelaughter's answer, then, I dunno, you tell us :eek:k:
 
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