What cars? Like Bowman said, 1911 model cars? All cars today have crankshaft position sensors that count the revolutions with 100% accuracy. They then display it typically on an LCD display that has enough resolution to be highly accurate.
The typical temp gauge doesn't display it with high accuracy, if at all, but the onboard computer knows it very accurately.
Few percent isn't good enough?
Nor the fuel gauge.
And who claimed the MPG reading had to be accurate to better than that for it to be useful, interesting, etc.?
The whole point is that the calculations are off by more than people think, so, the actual percentage matters greatly in that all the errors add up.
Speedo error adds to the fuel level error which adds to the fuel pump error which adds to the density error which adds to the atmospheric pressure error, etc.
All those errors add up, which is what my scientific mind sees.
I don't see mom-and-pop MPG-calculation accuracy anywhere near a decimal point, that's for sure.
But that's why I asked the question (which is still unanswered since references are all that matter - not opinions).
I agree with you that CR does a lousy job of testing some things, e.g., they once tested motorcycles and rated highly the "quiet" ones, where most bikers don't put the quietness as a critical factor.
Likewise, they measured mpg, where, again, most bikers don't really care all that much about fuel efficiency (although tank size and miles to empty has some bearing on the tourers).
But, still. You have to assume the engineers tested their opinions "more better" than Joe Usenet did. You just have to assume that this is the case.
So, what CR says goes on the list, along with Car and Driver and other hopefully reputable rags.
The part that saw that you didn't stop there, you went on to cite pure opinion pieces one after the other, as if they were gospel. Including totally stupid ones that claim that *all noise* from loud pipes goes rearward, not forward. You think that because someone posts something on a website, that it;s automatically meaningful, even when it contains total discrediting stupidity like the above.
What I think is that while claiming to be a scientist, you clearly are clueless when it comes to even the most basic science and scientific methods. Nor do you show any inclination to learn, ie you just totally ignored it when I immediately pointed out the most basic physics that even a child would seek to understand. Instead, it's off to find fluff pieces on the internet.
Clare, you're just sore because so many of us have taken you to the woodshed for all the stupid and incorrect things you've posted here, especially on electrical issues. Doug Miller hasn't been here in awhile, but boy he;s got your number too and has called you out on your BS many times. And I don't just come out of the woodwork and attack you either. Sure, if I disagree with something you post, then I;ll say so. But when I agree with what you post, I don't just sit there like an asshole and take shots at you. Both Bob F and I were on the same page here, on the same side, as you from the beginning. And I haven't blocked you either, that's the last refuge of idiots that aren't man enough to be challenged and defend themselves. It also leads to perpetual ignorance. Now, like I said, why don't you go get a room with your new buddy and jerk each other off some more.
For starters, I am not talking about a dashboard display provided by the manufacturer. As I've said repeatedly I use a ScanGauge II plugged into the OBD II bus. How accurate and repeatable is the ECU? Tach? That would depend on the smoothing algorithm for the display. Counting the ignition pulses is a no brainer. Distance? The unit can be calibrated for the rolling circumference of the tire. Variability on tire temperature and pressure? Sure. Injector timing? Temperature? How good is the sensor?
Fuel efficiency on a bike is highly variable. That's what happens when you have a drag coefficient like a barn door. The only thing that saves them is a low frontal area. Since I live in a state where there isn't a gas station on every corner I tend to be interested in those matters. I replaced the OEM tank on one bike because a potential 120-150 mile range wasn't going to make it.
I don't assume when it comes to engineers. I are one. Some are very adept at getting data that matches their opinions.
C&D is an entertaining publication geared to delivering advertising to the consumer. I have one magazine I trust -- Motorcycle Consumer News. There is NO advertising. If they test the Vincent Super Snark and it sucks that's what the review says. Usually there are several reviewers riding the bike since much is subjective.
Engineers and scientists rely on facts and data, rather than opinions. They may have theories, but then they test those, verify them and prove or disprove them. And they don't rely on opinions from random internet sites as data at all.
I think you're answering a different question than is meaningful to most people simply because most people don't have a ScanGauge II to plug into the OBDII port.
Most people have a tripmeter reading and a gas pumpmeter reading. Where they fill the tank and reset the tripmeter before driving away.
I can't find any reliable source that says what the accuracy or repeatability of that mom-and-pop tripmeter/pumpmeter calculation, but basic logic dictates that the errors compound such that there is likely (IMHO) no way to get anywhere near decimal-point accuracy, and worse, probably plus or minus 1 mpg is the closest anyone can get in terms of repeatability and precision.
So, someone's 20 mpg is really somewhere in between 19 mpg and 21 mpg.
It is amazing that even a faired motorcycle has the Cd of a semi truck!
I would hope full fairings would help.
I used to get about 100 miles to a tank (give or take), no matter what bike I had over the years (college days).
That's a lot more than I ever got on a tankful of fuel, at least in the olden days.
I are one too. Luckily, I don't trust my intuition. I'd rather trust facts.
They all are, to some degree. IMHO, C&D is better than Motor Trend, but they all get "freebies" that they supposedly test (with the marketing guy in the passenger seat feeding them exactly what to say).
Every rational person (and especially logical engineers and scientists), keeps a few grains of salt with them every time someone tells them anything.
You can also trust me to say it like it is (as I see it). I will try to back up my wild-ass guesses with references (when/if I can).
They (bikes) are pretty dirty. Over the years trucks have improved. You still see old school squared off tractors with no roof mounted fairings but I would guess many of those are O/O's who chose based on what a 'real' truck looks. The fleet operators go for the more efficient models and watch the fleet averages like a hawk. I've wondered how much affect the belly panels on dry vans have. I've seen a few attempts to smooth out the rear of the box too but that adds more work before you can back into a dock.
I assume they do. There are two problems. First is the bling factor again. Naked and retro bikes are in currently even with the metric riders. A really effective fairing would also be really awkward. Craig Vetter has been at it for ages and some of the stuff he inspired is sci-fi material;
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That plastic gets pricey too when you drop the bike. For a completely unscientific comparison, I have two bikes that are only similar in that they have 650 cc engines. The DR650 is a carbureted single, enduro styled bike with DOT knobbies and a minimal windshield. The DL650 (V-Strom) is a FI twin with a fairing and street tires. My mileage calculations make mom and pop look like EPA scientists -- rough division in my head of an inaccurate odometer by the pump gallons. I did go up a tooth on the DR's front sprocket to keep the highway rpm down.
Given apples and pomegranates, both can get around 50 mpg. The DR does it screwing around on dirt roads and reasonable highway speeds and the Strom tends to do it consistently. The difference is the DR at 80 mph is down in the low 30's and the Strom is still happily up in the '50s. More variables than a dog has fleas but the complete lack of aerodynamic finesse on the one really seems to hurt as the speeds climb.
The Sportster has a 3.2 gallon tank, runs in the 40's and I generally fuel at 110-120 miles. The stock DR tank was also 3.2 iirc so averaging out someplace in the 40's would put in a similar range. The aftermarket tank is 4.9, which gives me some insurance. There is a dirt road that goes over the divide into Idaho. I would pass the point of no return a little ways into ID and would have to ride out to civilization in ID to get back. This way I can screw around put on about 200 miles without getting nervous. The V-Strom has a 5.8 gallon tank but I generally fuel a little over 200 miles. It also has a relatively accurate gas gauge which helps. Of course, there's no petcock to turn to reserve when it starts to sputter so you damn well better be watching it.
Some of the Sportsters had a 'peanut tank' that was a little over two gallons. More bling, looked kewl, but I ride a little longer distance than bar hopping around town. Another gallon is good.
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