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Comment What Consumer Reports knows and when they know it (Score 1) 136

Consumer Reports provides such feedback regarding disparity between their gas mileage test and EPA stickers only occasionally, such as with their evaluation of the C-Max. If they give a table for the cars they review somewhere in some issue as to "EPA sticker", "Consumer Reports road test", and "percent disparity", I would like to know where that table is. The impression I get is that 1) they regard their road test as a "ground truth" for fuel economy and think of the EPA numbers as "made up", 2) if a reader wanted the EPA number, they could go look it up on FuelEconomy.gov. Their road test has also changed over time, making it hard to compare a new car model against a 20-year old car, and yes, some of us keep cars that long. I can't find in Consumer Reports back issues a good description of their road test conditions.

Has Consumer Reports ever set up a road test to replicate the EPA test conditions and used that to quantify road test/EPA test disparity?

They only mentioned the disparity for the C-Max because it was large, even compared to the Prius, which also has such a disparity. The tone they took was that the larger disparity for the C-Max was evidence of Ford "gaming the system." They only mentioned in passing that the C-Max was also much less underpowered than the Prius, without any discussion as to whether this performance fully accounted for the difference in gas mileage, whether this was a tradeoff that a consumer would want to make, and whether driving the C-Max more conservatively made up for the shortfall in gas mileage.

Indeed, the large disparity in the C-Max could be evidence that Ford is gaming the system, but Consumer Reports didn't do anything to pursue this further, unlike the lab that found a disparity in the VW Diesels and dug deeper. It could be that Ford is legally gaming the system in optimizing the C-Max for the narrow range of driving conditions on the EPA test while giving it a transmission tuning making it "more fun to drive" in more "normal driving conditions", hoping that their consumers would be happier with the better acceleration and that consumers would be conditioned to believe that the "EPA numbers are made up, anyway, and no one ever gets those." Or it could be that Ford has "pulled a VW" and not get caught, but Consumer Reports has passed on investigating this deeper to find out.

Consumer Reports also appears to lack curiosity regarding outliers in their own test results. I remember a while back they tested a Dodge Neon back when Chrysler made a car with that nameplate, with a 3-speed automatic transmission to boot, that got in the mid 40 MPGs on a test where competing cars were in the mid to high 30's. Did they rerun the test as a "sanity check"? Do they even know what the variation is on their test between successive runs?

I also notice that their gas mileage rating can fluctuate, often downward, from year-to-year when they retest the same make and model of car. You also see this in the EPA numbers. Some of that may be transmission and engine retuning to trade more "pep" for less gas mileage, especially in the years when gas prices were in decline. But a consumer gets to wonder if the same kind of car can vary in gas mileage and by how much. That the expectation is that the EPA gas mileage is "made up" bakes into the system that it is hard to make the case that you bought a "lemon car" with bad gas mileage. A gas mileage complaint is really hard to make stick with the guys who sell and service your car because they will always turn it around and blame it on your driving. Did Consumer Reports ever try renting, say, about a half dozen cars of the same make, model, and year to see how consistent they are?

Yeah, yeah, Consumer Reports is a non-profit with limited resources in the amount of testing they can do. But given that gas mileage is such an important factor in satisfaction with an automobile purchase, and given that it is so hard to benchmark your car against a standard to check if you got a gas-mileage lemon (I suggest a method for a road test comparison against EPA -- can anyone tell me how to benchmark against the Consumer Reports road test as I don't even know what that road test is?), Consumer Reports could do more on this score. Remember, it wasn't Consumer Reports who uncovered the VW Diesel cheat.

Comment What the EPA test really measures (Score 4, Interesting) 136

The EPA tests were originally developed to quantify pollution generated by cars in the L.A. area, and using those tests to quantify gas mileage came later.

The EPA city cycle was not meant to represent the stop-and-go driving in Manhattan during rush hour. Rather, it was intended to be typical of an automobile trip in the L.A. area conducted on "surface streets", meaning major arterial roads that have stop lights and are not freeways. The average speed of that cycle is about 20 MPH. The EPA highway cycle was not meant to represent bombing down an open Interstate at 10-over a 70 MPH speed limit. Instead, it was to represent a trip on the 405 freeway in Los Angeles in the days before that road became a parking lot -- the test was meant to represent "moderate traffic" levels where the average speed is about 50 MPH.

Not only may your miles-per-gallon vary, the amount of BTUs in a gallon of gas can also vary downward from an alcohol-free summer blend that was probably the standard for the test -- the test conducted on rollers somewhere in Ann Arbor, MI doesn't actually measure the quantity of fuel used but instead measures the combustion products out the tailpipe and performs a mass balance with that standardized gasoline.

Taking the lower BTU fuel you may be getting into account, if you start the car engine from cold on a 70 deg-F day, don't run the A/C, and drive for about 10 miles in traffic where you average 20 MPH, you will roughly reproduce a city test, and I have found that the reading on a Scan Gauge, calibrated to tank fills, will get within 5 percent of the raw city numbers available here https://www3.epa.gov/otaq/tcld.... These numbers are considerable higher than the window sticker MPG rating available here https://www.fueleconomy.gov/. Driving on a not-that-hilly road (do this in both directions and take a harmonic average to compensate for net elevation change) on a 70-deg calm-wind day with the A/C off at a constant 55 MPH, if you can do that with angering other drivers, is a good proxy for the EPA highway test and will also get you within 5 percent.

"But no one drives that way!" someone will shout at you, and this may be true, but if you want to reproduce the EPA test conditions to see if you can match the (raw) EPA numbers, this is the way to check that.

The sticker MPG at fueleconomy.gov has had more than one "adjustment" performed to down rate it from the raw MPG. This was done because the published EPA ratings made people who considered themselves to be "good drivers" feel bad about themselves and their expensive new car purchases, and we cannot have any of that. Or rather, the "consumer" gas mileage numbers were proportionately reduced to "better reflect how real-world driving conditions on more congested city streets and with higher speed limits on highways affect mileage" whereas the Federal Test Procedure and the raw numbers for computing CAFE (corporate average fuel economy) were left the same so as to not keep changing the rules to which the car companies had to comply.

Now the down-adjusting is based on fleet averages, and your car may vary. A case in point is that Consumer Reports praised the Ford C-Max hybrid as being a lot more "fun to drive" than the Toyota Prius but slammed it for being much further off the EPA sticker in real-world driving than the Prius. Well, duh, Consumer Reports! Were you to drive both vehicles in a true "EPA city granny cycle", they probably would get proportionately higher than the window sticker as is the raw "test car" number. But left to the lead foot of a "normal driver", the C-Max with its bigger gas engine will indeed accelerate better yet use more gas than the small-engine sluggish Prius.

I also expect "eco-cars" like the Prius to suffer more from "normal driver" in relation to EPA test cycle driving because their power plants are more matched to the "granny cycle." A real "muscle car" may suffer less mileage loss from "aggressive driving" because when its motor is lightly loaded in the EPA test, much of its energy is going into overcoming wall thermal losses, internal mechanical and manifold vacuum throttling friction on account of its large displacement motor.

There are two points, however, that merit further investigation by auto geeks. One, the EPA test takes place on chassis rollers in that Ann Arbor, MI lab and not on a test track. The friction coefficients for those rollers of the form A v^2 + B v + C = F where v is velocity and F is the total drag force experienced by the vehicle, those coefficients are supplied to the EPA by the manufacturer based on their test-track roll-down tests. I have seen some "anomalies" in those A, B, and C friction coefficients where a particular car model is an outlier from similar cars. Are the manufacturers honest? As the day is long!

The second point is amount of manufacturing variation in cars and car engines. Does anyone know this? In other words, a 50 MPG Prius will get less than 50 MPG in practical use, but it should somehow get proportionately double the mileage as an SUV with a 25 MPG rating? But if I rented a different Prius each week, would I see the same gas mileage, or would that vary because each engine and transmission has a different amount of friction in it? Could I end up with a "lemon" car with bad gas mileage for that particular make, model, and engine?

Comment "Regular maintenance" (Score 1) 271

And what is "regular" maintenance on a grease fitting-free sealed and not serviceable component?

Is it anything like the "tuneup" the President of the U.S. was recommending for owners of cars with 100,000 mile spark plugs controlled from a sensor buried in the flywheel housing?

And criticizing car owners "for expecting warranty service out of warranty" is not "taking sides in an all out war from Mom's Basement" when in response to regulatory pressure and market competition, there is ample precedent for automakers offering outright repair/replacement for items out of warranty that fail well below expectations given the current state of technology?

The "vibe" I am getting about Tesla is that they are a startup automotive company in a field of alternatives with decades of experience with how things break and how long they last and how to engineer things to tolerate hard use and go the distance? That in being an "early adopter" of a high battery-capacity high-performance all-electric car, owners are taking the risk associated with a not-very-high-volume-production not-on-the-market-for-very-long car?

And that for the price of one of those babies (the car, not the owner), you could get a Camry for each of Mom, Pop, Junior, and Sis? And that this huge financial outlay may make an owner, don't know, feel "entitled"? And "dudes on Slashdot" are rallying to Tesla's defense because they regard this story as ammunition for right-wing green-energy haters?

And that 3100 dollars is a bit "stiff" to replace one failed control arm and ball joint?

Comment Mexico, Russia, and the Middle East (Score 1) 39

These dudes in Mexico, Russia, and the Middle East are pumping out "one of six air pollutants regulated by the U.S. Environmental Protection Agency."

I'll bet those dudes are now worried about what happens next . . . next thing you know it, the U.S. President will give a speech subjecting them to a good scolding.

Comment Where I store cold, dry air (Score 1) 324

is in my basement walls. The walls not only accept heat, if they are dry, they soak up humidity.

Not enough storage between seasons, although the basement chilled in winter delays, perhaps, by a week or two turning the A/C on. But certainly enough storage to not have to run the A/C flat out in the heat of day where it consumes more electricity than running in the cool of morning.

Comment Steep mountain grade (Score 2) 324

OK, something here doesn't "compute."

The cost and challenge of pumped-storage hydro is finding an available mountain or hilltop where you can store enough mass in the form of water. Here you are storing mass on top of the hill in the form of train cars and electric locomotives. If you had enough room on a spare hilltop to park the train, wouldn't you have enough room to put in a bunch of water tanks, or better yet, and open-air pond or maybe an underground water-storage cavern.

And if you are going to have the train make a bunch of trips to move gravel to the top of the hill and then later bring it back down, why would you not have room to store water? OK, water is less dense than gravel, but water can be pumped as opposed to loading and unloading gravel from those train cars and the attendant friction loss?

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