2011 Chevrolet Cruze LTZ: Hot Hot Heat and MPG
June 17, 2011
Day Two of my quick Phoenix excursion in our 2011 Chevrolet Cruze dawned just as bright as the day before. It was clear from the outset that this was going to be another hot one.
First thing in the morning I topped up the fuel tank to isolate yesterday's long freeway drive from today's in-town driving. In the relatively cool Phoenix morning air, the heat-related turbo boost problems I had yesterday were gone.
The run from my home in Orange County to here had been a vague attempt to duplicate the conditions of the fuel economy run I made recently in a 2011 Chevy Cruze Eco. But California and Arizona freeway speed limits are set at 70 and 75 instead of 65 mph and the prevailing speed of traffic is even higher than that. I didn't dare set the Cruze on cruise at a pokey 65 mph like I did in the Eco on the east coast. Instead I settled on a 70-mph target speed to keep things close without making myself into a rolling chicane.
Our Cruze LTZ with its 1.4T motor and 6-speed autobox is EPA-rated at 24 city and 36 mpg highway. I was able to match the Cruze Eco's 42-mpg highway figure a couple of weeks ago. Could I achieve 36 mpg in the Cruze LTZ here?
The short answer is no, not even close.
Our Cruze LTZ gulped 12.19 gallons of unleaded after 364 freeway miles on a run that included a smaller number of side trip miles than I made in the Eco. That works out to 29.9 mpg, a full 6 mpg shy of this car's EPA highway rating.
Driving at 70 instead of 65 mph probably accounts for no more than 1 or 2 of the lost mpg. So what's left? Heat. Oppressive desert heat. My schedule forced me to make the drive in middle of the day, and the outside air temperature gauge hovered between 105 and 111 for at least 275 miles of the trip. Perhaps the boggy low-speed behavior I experienced was an overt sign of a more subtle loss of turbo efficiency that blanketed the entire run.
But that's not an entirely comfortable explanation because the Cruze also did worse than Erin in the portlier Buick Regal turbo, a car rated at only 28 mpg on the highway. On a similar hot desert run at a higher cruise control set speed she managed 30.7 mpg. She managed 30.9 mpg on a return trip run at the same 70-mph target speed I used for this run. In short, her Regal is kicking my Cruze's ass.
The only other difference I haven't mentioned yet is the fuel used. Erin used 91-octane supreme in the Buick while I stuck with 87-octane regular in the Cruze, just as I had in the Eco test weeks earlier.
What conclusions can we draw from this? Not sure. I need to drive home and bake in the return trip data first.
Dan Edmunds, Director of Vehicle Testing @ 11,107 miles