Quote:
Originally Posted by Thai
The problem with CR is that the fuel economy comparison b/w vehicles is not done on the same day with the same driver etc.. I know that they use the same route and so on, but, scientifically, the result is invalid because there are still too many variables left unaccounted for.
EPA, on the other hand, is done under controlled laboratory conditions where variables are accounted for. So, in this case, the numbers can be used to compare b/w the vehicles. Whether it reflects real life or not, i don't know. But, if you have the same driver on the same day and on the same route, i still believe that EPA fuel economy differences will prevail.
From my experience with my NA cars, EPA is pretty accurate. Even in my Prius, the EPA numbers are pretty accurate...and i consider myself a "normal" driver...in other words, i don't go out of my way to conserve gas nor do i have a lead foot.
For turbos, i am getting mixed feedback. Edmunds got horrible gas mileage on the Chevy Cruze with 1.4 turbo powertrain and automatic. My brother's Cruze with 1.4 turbo powertrain and 6-MT is getting amazing mileage!! On the highway, he is easily hitting 44 mpg AVERAGE from Austin to Houston on the computer! He drives at 70 mph. Overall, since owning the car (at least 700 miles i think), he is averaging around 37 mpg (city and hwy mix)!! (There is a 5% difference in the computer reading to real life.) Even with the real life adjustment, my brother's Cruze is getting near hybrid mileage, certainly on par with midsize hybrid sedans! I think that Edmunds' Cruze is a 2010 model...and my brother is a 2012 model. I read that Chevy is making small changes on the assembly line since 2010 to improve fuel economy.
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The problem with the EPA's numbers is the fact that they run the car on a flat treadmill through a prescribed start, speed up, slow down, stop, speed up, slow down, stop, rinse, repeat pattern that only runs 11 miles. Throw up enough OD gears and 'early shift' logic and this test is easily sandbagged.
The fact is that the EPA doesn't test most vehicles. They send the pattern to the manufacturers who can then tweak shiftpoints, gear ratios, etc to match that known pattern. This is why I like reviewing the CR numbers. The manufacturers aren't tweaking their vehicles to that test. To me, the EPA method is like giving students the test, letting them go home and figure out the answers, and then come take the test. CR buys their cars off the lot and runs them through their battery of tests and you get are testing the car in a scenario that it wasn't tweaked and massaged for. It might be different days, different drivers, but I'd say that CR takes measures to ensure that their testers keep that as uniform as possible. Certainly not invalid.
That is great that your brother is getting good gas mileage. The Cruze eco also has 3 overdrive gears, low rolling resistance tires, and all sorts of aero aids (shuttered grille vents, belly pan, etc). It should be getting 37mpg, especially if he lives somewhere relatively flat (sounds like he does driving austin to houston). He'd probably get or beat the EPA ratings in most vehicles because his driving pattern sounds like it is pretty ideal.
My point is that the turbocharged engine isn't solely responsible for that gas mileage. Especially considering he does so much 70mph driving, the OD gears and aero aids do a lot more than the engine that only needs to pump out 30hp or so to keep it moving. It can easily do that off boost. Back to my point about turbochargers not really providing much gas mileage benefit, lets compare CR's Cruze 1.8L v 1.4T numbers.
Model :: 0-60 :: 1/4mi :: City :: Hwy :: 150mi :: EPA City :: EPA Hwy
1.8L,6AT :: 10.5 :: 18.0 :: 17 :: 36 :: 34 :: 22 :: 35
1.4T,6AT :: 9.8 :: 17.6 :: 17 :: 36 :: 35 :: 24 :: 36
For all practical purposes, the cars return the same numbers with the 1.4T being marginally faster and marginally more efficient. If I'm recommending a car for my mom, I'm going to say that the 1.8L is the better buy because it costs less up front, returns practically the same numbers, and has a far less complex engine. If I'm buying for performance, I'm not buying a Cruze. ;)
Just to show why EPA numbers alone aren't sufficient, lets pull in the Civic and Corolla...
Model :: 0-60 :: 1/4mi :: City :: Hwy :: 150mi :: EPA City :: EPA Hwy
Civic EX :: 10.1 :: 17.8 :: 18 :: 43 :: 37 :: 28 :: 39
Corolla LE :: 9.9 :: 17.6 :: 23 :: 40 :: 39 :: 27 :: 35
That is a wildly mixed bag when you look at all the numbers. The 4AT Corolla returns fantastic city numbers while the Civic has great highway numbers... except for the 150 mi trip where things tend to even out. If you do a lot of city driving, just going by the EPA numbers would say that the Civic is the way to go, but the CR numbers say that the Corolla is the superior car.
