271–280 of 336 posts
My 2009 Jetta was rated at 29 city, 33 combined and 40 highway . Based on my fuel records, I got 33 city, 36-38 combined and 50 highway.
That means it out-performed the EPA estimates by 25% highway, 12% combined and 14% city.
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That both suprises me, do you have any sources? Honest question, both seem counterintuitive. Maybe I am actually fed enough "feelgood" information in the past.
http://www.theguardian.com/environment/2015/mar/05/industry-...
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Actually, it depends. Modern cars do better in rolling hills than on perfectly flat land, since they can cut fuel entirely on the downhill, and the climbs don't require that much extra fuel over just maintaining speed. Now, mountains are another story, of course. Some good stuff in this SE question: http://physics.stackexchange.com/questions/6220/can-a-car-ge...
I cannot imagine a cyclist imagining this to be true! Obviously aerodynamics play a part, however the cyclist's 'engine is cut' on the downhill and on big cross country roads no brakes need be used on the descents. When the 'engine' is on it goes at a certain not-quite-racing amount whether up hill or on the flat. But place a hill in the way of A to B and vastly more 'fuel' is used than A to B 'going the flat way'.
What if you can start by coasting 90% of the distance with zero expenditure of energy? What if it was 95%? Now assume that your chain is extremely rusty (low efficiency drivetrain). Would it be possible that the energy to go the short distance up the remaining hill (after coasting downhill and halfway up the other side) might be less than overcoming the friction of pedaling the whole way?
I'm not certain that they occur on a bicycle in the real world (perhaps you need a custom crafted rusty chain that has essentially constant high losses regardless of pedaling speed), but I think there are cases where the variable losses due to friction might make the hilly case more efficient than the flat.
(Yes, I realize that chain friction is not the dominant factor in the real world. It's a stylized example.)
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I actually drove my Golf TDI at around the level of 5l/100km in Berlin for many years. Carefully. My girlfriend's Polo is significantly below that. Of course, these cars aren't ton and a half, but more around a ton.
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VW Up!: curb weight 920 kg, max total weight 1290 kg.
Audi Q3: curb weight 1460 kg, max total weight 1980 kg.
Audi Q5: curb weight 1935 kg, max total weight 2460 kg.
So, modern passengers are very heavy...
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No matter how careful I am, it's hard for me to get lower than 130% of the fuel consumption reported by the manufacturer. Perhaps I can do 120% of the reported consumption at 90 km/h, but I can hardly get lower than 140% on the highway (130 km/h) and in city traffic.
My Subaru Outback has been a nice surprise in this area. The combined highway/city mileage on the sticker was 24 mpg, and I've been getting 27 or 28 mpg for the entire 2 years I've owned it. For a while I was commuting between Denver and Boulder (about 45 miles each way) five days a week and taking it up to the mountains for hiking or skiing every weekend, so it's been over a wide variety of terrain. I'm using the nu…
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That's like saying someone threw a rock at you and because you didn't look around before it hit you, its your fault. The cheating is the problem, not the fact that people are ignorant about it.
no, its like saying "caveat emptor" http://rockyroadblog.com/caveat-emptor-vetting-mpg-claims-30...
Obviously this is only as good as the way I drive (or my wife) and is heavily dependent upon if I hit traffic, mostly drive in the city or go on a road trip.
It really is an interesting thing to keep track of.
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I did some tests on a long drive last week, for the Smart Forfour I had this was the fuel consumption. It was all along flat, straight parts of the highway. Reports were based upon the cars own fuel efficiency monitor. - 135 km/h 7.8l/100km (30 mpg) - 125 km/h 6.5l/100km (36 mpg) - 115 km/h 5.4l/100km (43 mpg) I never realised speed made such a difference! (Mpg is US gallons)
The reason why it matters is that air resistance is proportional to the square of your velocity. At high speeds that term dominates.
source: presentation by Dr. Rizzoni at Center for Automotive Research at OSU
Here is one. My Porsche has a display which tells you the MPG. However the car display is consistently between 1 and 2 mpg better than what I calculate after filling the tank and doing the math. And I repeat it's consistently worse than the display which calculates the mgp per tankful which is probably what most people rely on. I've been meaning to bring this up with the dealer but haven't so far. This is in addition…
Yeah, mileage computers in cars are known for being a bit optimistic. It's not hard to beat the EPA highway number for your car. Put it on the highway, cruise at 65mph, done. The EPA test cycle doesn't even exceed 55mph, but it has quite a bit of slowing and speeding up, so you can beat it with a consistent cruise a good bit over their 55mph number.
When your speedometer shows 100 km/h, it is permitted that true speed is 90 km/h, but it is not permitted that the true speed is 101 km/h. And the same variance applies to odometer, of course.
Things like tyre wear and pressure have a noticeable impact on what both meters show, and manufactures have to stay on the safe side, by law.
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> Saying a manufacturer deserves extra scrutiny can absolutely be inferred to be an accusation of them reporting false numbers, i.e. lying. > My reading comprehension isn't at fault here Except that I very clearly said "I can't discount the possibility of something else is going on, such as an influx of a different type of car for GM over that period, I haven't read yet how they normalized the study and accounted for…
> You ignored clear text from me saying that it didn't necessarily indicate GM was at fault. What am I supposed to infer from that? I didn't ignore anything. I said the source of data is not irrelevant. That's my entire argument. And I was specifically refuting your thesis that the source of data is irrelevant . and, "as to the matter at hand", yes, driver habits can account entirely for the discrepancy in numbers. F…
Please stop trying to tell me what my thesis is, as you've misunderstood my statements. The portion of the comment I was responding to is "In my anecdotal experience, drivers tend to get much lower than the manufacturer mileage because they optimize for things other than fuel economy (e.g., speed)." That, by itself, is irrelevant to the question as to why one manufacturer has vastly different numbers than another. As to testing methodologies, yes, this could entirely be testing error. I've never stated my opposition to that possibility. I have repeatedly stated my only intention was to say these numbers need more investigation.
I'm done trying to discuss this with someone who ignores what I actually state in favor of what they decide I must be implying.