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Comment by dexwiz | Hacker News Reader

Apple should have added a Amp or Watt usage number, not removed the estimate. Similarly, most new cars have fuel estimates on their dashboards. But its not just miles to empty, its also miles per gallon. So drivers can get feedback on usage rates versus total capacity.

I imagine the argument about this, is that most people don't have any handle on what a Watt or mAh is. But people don't have a good handle on how far 25 miles is, or how much a gallon is in comparison to their tank. Think about it, you rarely see the fuel you put into your car beyond a few drips at the pump. And while you may know that its 25 miles between your house in work, if I took a random point on a map and said find something 25 miles away, with no scale, most people couldn't do it. Gallons and MPG are just arbitrary numbers that consumers have learned how to compare. If you exposed those numbers, they would get a better handling on what their device consumes, and how their activities affect it.

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They still have the percentage indicator, which is presumably directly proportional to mAh remaining, and people generally have a good understanding of what percentage is.

Using your analogy, your gas gauge doesn't show the number of gallons, it shows a relative level.

His point is that Apple should show the energy consumption rate in addition to the percentage indicator, just as cars show fuel consumption as mpg and fuel remaining as a percentage.

Older gauges just showed percentages, but many new cars will tell you gallons, current MPG, and an estimated distance to empty.

How far back do we have to go to get to cars that just showed percentages, cause I have literally never experienced one in my life.

Even my model year 2000 clunker has instant MPG, average MPG, miles to empty and a gas gauge with actual gallons.

My 1999 Camry has a dial that shows full, 3/4, 1/2, 1/4 and a red line.

My 2011 only has the gas gauge, without any gallon markers on it and numerous 2016/2017 cars I've been test driving haven't had it. It's certain classes of cars that have had it for quite a while, nowhere close to all.

My 2007 Toyota Matrix just has an analog fuel gauge that goes from Full to Empty with marks for each quarter. No gallons, no MPG calculations.

Not far. My last car was a Toyota Yaris 2001, and the display (center top) only has percentage, and it's not very fine-grained: http://i.imgur.com/ESXap6F.jpg

My 2003 VW Golf has a gas gauge that shows percentages - the individual markings represent 12.5%, not individual remaining gallons (it's a 14.5 gallon tank, not an 8 gallon one) My mother's 2009 Jetta has similar. Whether or not the instrument cluster implements a multi-function display that shows instant/average MPG or miles to empty, every car I have ever driven, from the 80s clunkers of my youth to brand shiny new rentals has had such a fuel gauge.

Such a style is cheaper to implement. Resistive float sensor in the tank, run a wire to a mini 90 degree needle gauge in the instrument cluster, done. Instant/Average MPG and miles to empty are additional fanciness that up until recently, came standard only on higher-end cars, or was part of an optional package that may or may not be avail on lower end brands/models.

I thought that the gallons calculation used the same cheap mechanism, just adding a trivial percentage left * capacity calculation.

2009 Civic LX - gas gauge with 20 squares, no mpg at all, no actual gallon number.

2005 Ford Focus, just a gauge. It has percentage fuel on the OBDII interface but not MPG estimates. Some cars might have it on the OBDII if they don't have a gauge.

You have to go back pretty far. In the wake of the 1973 Oil Crisis, most new cars had MPG displays.

The 2012 Mazda 6 doesn't show MPG, but it does calculate it and expose it over ODB II

The only car I've ever had that showed MPGs was a 1990 Audi.

Everything else (1998 Toyota Camry, 2002 Chevy Impala, 1997 Ford Ranger, 2005 VW GTI) have only had an analog fuel gauge.

My car tells me how many miles I have left by basing its estimation on my consumption over the past 30 miles. It has been pretty accurate.

I think you can liken the situation with macOS to switching from a gas car to a Hybrid. Gas cars have relatively predictable MPG. Hybrids don't. Your Hybrid can go from 25MPG up to 100+MPG depending on the way you drive, and it can bounce back and forth between the two constantly during a trip. Now, I have to admit, I don't own a car at all and so I don't know if hybrid cars actually try to estimate mileage remaining, but if they do, then surely their estimate will change wildly as you change how you drive (e.g. smooth highway driving to traffic jam to city driving to aggressive driving to defensive driving, etc).

I own a Prius. Fuel efficiency doesn't seem to be any more variable than the conventional cars I've driven. The distance remaining estimate seems reasonably accurate in that it goes down ~50 miles after I've driven 50 miles.

Whenever I drive a Prius with ZipCar, the MPG numbers change wildly while I drive, and even the average MPG can change by 5–10 miles over the course of a decent drive. I assume the distance remaining estimate is based on that average MPG number, but since I have seen it change by significant amounts, that means the distance remaining estimate certainly is reasonably inaccurate.

If you always drive your car in the same manner then sure, you'll probably have a reasonable estimate. But similarly if all you do with your computer is browse the web, you'll also have a predictable battery remaining estimate. But while many people do drive fairly consistently, your usage of your computer probably has a lot more variety in terms of energy impact.

That's why you average it over some time, not just take the momentary usage.

I'm guessing Apple don't want their customers worrying about the way their computer habits affect battery usage. They sell premium hardware that "just works". Reminding the user they need to keep an eye on what they do with the device seems incompatible with that mandate.

> its also miles per gallon. So drivers can get feedback on usage rates versus total capacity.

I don't know anyone who actually adjusts their driving to try to push the mpg metric up. I'm sure there is some tiny subset of the population that does this but in general this isn't actually a useful number except to make people annoyed that they aren't getting the EPA estimated fuel efficiency.

Car manufacturers don't provide this because it's actually useful. They provide it because it's easy and people like bells and whistles.

> if I took a random point on a map and said find something 25 miles away, with no scale, most people couldn't do it.

I don't think this is a particularly meaningful observation since maps have scales precisely because it's basically impossible to know the distance between two points without a scale. This isn't a function of not intuitively grasping what a mile it. It's a function of maps being scaled. Even if you have an amazing grasp on distances it won't directly translate to the map.

raises hand

I'm not a hardcore hypermiler, but just doing little tricks (minimizing throttle/braking, "reading" traffic, maintaining an appropriate speed/distance relative to other cars, etc) makes quite a bit of difference in the commute. I have a small (tiny?) turbocharged car and can get 40-42 mpg on my commute between Denver and Boulder.

I get ~18 MPG in my Impreza, and even though my fuel mileage sucks I still take steps to improve my fuel mileage. Just because my commute is short and I'm flooring the car down the on-ramp to the highway doesn't mean I don't want to take steps to improve my mileage within the boundaries of how I want to drive my car. For instance, is it better to be in second or third gear when in slow but flowing traffic?

In the same sense, I'd like to know how my computer usage is affecting my battery life. Do the extra tabs I have open in chrome matter, or should I bookmark them and close them until I need them? Just because I value one thing over another, doesn't mean the less valued option doesn't come in to play when making a decision.

> For instance, is it better to be in second or third gear when in slow but flowing traffic?

It doesn't really matter because your gas mileage is likely dominated by things like flooring it down on-ramps.

But 3rd is more efficient in the case you describe.

I know my gas mileage is dominated by flooring it down on ramps, but my mileage is still affected by a lot of other factors. I track basically everything I do with my car, along with mileage, and small things make a surprising difference. I can detect a change in my fuel consumption based on what tires I have on my car, how old my oil is, whether my roof rack is on my car, and whether I have my bike mount on my rack.

Those effects are noticeable on my normal commute, where I travel 8 miles and spend most of the time going less than 30 mph, where aerodynamics doesn't matter that much. When I take a road trip (and thus don't have to perform any suicide merges), the difference any of these things makes is quite substantial. My summer tires are each about an inch wider than the tires I have mounted on my old rims, and switching to the narrower tires makes more of a difference in mileage than taking off the roof rack. With the narrow tires and no roof rack, I can get about 36 miles per gallon at 55 mph, and with my winter tires and my roof rack on my car I can't even approach 30 MPG.

For a tech-related example: I prefer to use my phone with the backlight turned all the way up, even though it uses an additional 15% of every full charge, but I uninstalled the Facebook app because it used 3% of every battery just running in the background.

I'm just trying to be efficient in my own way, I'm not competing on efficiency.

Turbo or non-turbo Impreza? I had a WRX (turbo) for nearly 10 years and I don't think I ever got below 25. I'm surprised at 18 - I would consider that really low. I don't know your scenario, but I would guess that you could do much better than that with just a few changes. I've never had to floor it on an on-ramp, but I haven't driven everywhere in the US.

I assume you have a manual transmission? Which engine do you have?

A huge part of why my mileage is terrible is because I basically have the worst possible commute for fuel mileage. live in Chicago, which supposedly has the worst traffic congestion in the country. My commute is only about 8-10 miles, but there is a lot of variation in speed. I can go from stopped to 65-75 miles an hour back down to stopped several times on my commute. The commute takes about 30 minutes, and I spend a lot of time idling.

Obviously that is a ridiculously low mileage for a car, even given the conditions. My fuel mileage never dips below 18 mpg for an entire tank, but it rarely goes above 20 mpg unless I leave the city. Looking at similar vehicles on Fuelly, I don't think it's that far out of the norm.

My Impreza is a 2010 OBS, with the 2.5L NA EJ25, and a 4EAT. I think what really kills my mileage is the 4-speed automatic. From what I've read, it's absolutely brutal on fuel efficiency compared to the 5 speed manual. The NA uses a lot more fuel than the turbo when just puttering along as a result of its higher compression (10.0:1 vs. 8.2:1) It's not necessarily a negative - my car is faster off the line than the turbo, especially after sitting in traffic on a hot day.

I know the WRX has a DOHC engine, whereas the 2.5i is SOHC. That probably makes some difference in efficiency, though I don't know how much.

On top of that, I almost always have my roof rack on if I'm driving in the city, and I usually have a bike rack mounted as well. Plus, I have the hatchback, which I've heard also impacts mileage, though I have no idea if that's true.

I've also replaced the somewhat narrow stock-all seasons with wider and softer tires summer tires. I run high sidewall winter tires on steel rims in the winter, which weigh a lot more than the stock alloys/all seasons.

Regardless, the Impreza really sucks at city mileage compared to other cars because of the added weight and drivetrain losses of the AWD. (As you probably know) It's really no surprise the 2.5i and 4EAT have been replaced by a much smaller engine coupled to a CVT.

Yes, I had a manual transmission. I assumed your comments regarding "second or third gear" implied you had a manual transmission. Automatics have come a long way in the past few years in terms of fuel mileage, but "slushboxes" like yours are probably the worst. I didn't know the Subaru automatics were that bad. I do know the new 2.0 with a CVT yields good results. It sounds like your driving pattern forces you to be in the worst fuel mileage ever (lots of time idling plus several bursts up to 75? ouch!). I assume you've explored other routes for your commute. Even something where you are driving slowly but not stopped/highway speeds should give a marked improvement.

The hatchback probably doesn't impact your fuel mileage much. I don't think the difference between DOHC and SOHC is going to have any measurable impact on fuel mileage either. Nor would I assume that a compression ratio change does that much. Your final drive ratio is probably the most significant impact. Additionally how much time you spend in "lockup" mode (where the fluid clutch is essentially disengaged and the engine crankshaft is directly connected to the driveline) is a major contributor. The roof rack absolutely impacts fuel mileage as Consumer Reports demonstrated: http://www.consumerreports.org/cro/news/2013/07/tests-show-b...

I use the manumatic function a lot in my 4EAT, because it always seems like it's in the wrong gear otherwise. I test drove a 5 speed and I hated it, cause the gearing seemed horrible for the speed limits which are really common around me.

Anyways, I take the highway to work, and I take a short stint on a highway and then surface streets on my way home. On my way home I run in to something like 40 stop signs. Pretty much every intersection has a four way stop for a few miles of my commute.

I can actually quantify how much the roof rack affects mileage, because I track whether I have it on my car or not in addition to my mileage.

On my way home I run in to something like 40 stop signs. Pretty much every intersection has a four way stop for a few miles of my commute.

That just screams "hybrid" to me. Wouldn't a hybrid or EV be the perfect vehicle for that scenario?

Does the MPG indicator actually enable anything? You can do all the things you describe without it. It's hard for me to believe that there's anyone independently discovering from their car's MPG indicator that minimizing throttle/brake usage improves mileage.

MPG indicator gives real-time feedback about what I'm doing. I could do everything without it (and did in the past) but "calculating efficiency by doing math at fill time" isn't granular enough. I don't think I could get that extra 2 or 3 MPG.

shrug None of the things you mention require constant feedback to understand. Heavy throttle followed by braking is just turning gasoline into brake wear. You know that already.

In Germany, demonstrating that you drive in a way that conserves fuel is part of the driving test. E.g. if you fail to shift to a higher gear when appropriate or shift down to brake that can be part of the reason you fail the test.

The modern Bluemotion Golfs I have driven seem to want you to drive in 6th at 30mph. This combination also results in an annoying drone coming from the engine which I can't stand. You can't accelerate in that gear. Also, I don't take instructions from an arrow on a dashboard telling me what gear to be in. That's my judgement to make based on road and traffic conditions.

The "shift up" recommendations to me seem like an attempt to replicate the ideal conditions under which the official efficiency tests are done - and we all know about /those/ figures...

Well, you're supposed to shift down before accelerating.

6th to 2nd is a heck of a downshift. It's hard for me to imagine driving around at 30 in 6th, too. The engine drone would be pretty obnoxious.

30 mph (almost 50 km/h) usually works very well on 4th in a 6-gear box, including accelerating, especially TSI engines which have a superb torque already on very low RPMs.

This in no way indicates the usefulness of the MPG indicator that most cars have. You can drive efficiently (or inefficiently) without it.

You can make assumptions about what's probably more efficient, but you can't confirm them without knowing how much gas you've consumed, and that takes several hours to justify stopping to refill the tank. Empty/full gas gauges have a pretty bad margin of error for this, compared to the ECU knowing how much gas has been pumped from the tank and/or injected into the cylinders.

This is kind of absurd. This is like saying you can't know that running sprints burns calories unless you have real-time feedback by hooking yourself up to a oxygen consumption meter.

You don't have to measure for yourself at all. The things you can do to save gas are well understood. If you generally just don't trust others' fuel efficiency guidance, I'm not sure why you'd trust someone else's mpg estimate either.

Is the air conditioner more efficient than suffering drag from open windows? Each has been commonly recommended at different times, and the correct answer depends on your compressor and body shape. The optimal cruising speed might be anywhere from 40 to 60 MPH, depending on your engine torque, transmission, and tires...

So you're trying to decide if you're better off with the A/C on or the windows down and you trust the short-term estimated MPG over the measurement you could do yourself? Fill up the car and turn on the A/C, drive an hour. Refill the car and record how much gas you put in. Turn off the A/C, roll down the windows, drive another hours. Refill and record. Now you can answer for yourself.

I get the logical appeal of the immediate feedback MPG meter, but I'm not clear how accurate these things are (vs meters on the gas pump, which are regulated to be within a tight spec). I'm also not clear how useful the MPG right now is vs the MPG over the past hour. I've seen only one car that let me reset the MPG meter and measure for an arbitrary period of time that I control, and I still have no idea how accurate it was. (Yes, I'm sure there is more than one car with this feature. I've only seen it once.)

Again, I just generally don't buy that instant (actually averaged over some amount of time that you don't control, with some accuracy that is likely not guaranteed) MPG estimates are all that useful. Are you dedicated enough to efficiency that you'll drive without A/C in the summer to see if it's better but you somehow don't care enough to bother recording actual gas usage? Who are these people willing to drive without A/C to save a MPG but too lazy to confirm that it really works? Or realistically is this one of those things where you turn off the A/C, glance at the MPG estimate and see it went up from 20 to 22, and assume that you've got a definitive answer despite not knowing anything about the margin of error for the MPG estimate?

It's… complicated.

On one hand, instantaneous mpg is seriously misleading. To me, accelerating efficiently means maximizing the amount of acceleration I get per unit of fuel—doing that does NOT maximize instantaneous mpg, but ideally finds the optimal point on the fuel-consumption-rate*time graph that you actually care about.

On the other hand, real-time feedback is probably better for the not-exactly-scientifically-rigorous way people learn, and it can be useful for noticing unexpected behavior not covered by intentional experiments.

A realtime unit-less fuel efficiency gauge in a U-Haul clued me into non-ideal behavior from the automatic transmission climbing hills. Feedback from this dumb gauge caused me to adjust my driving, which meant only my first tank of gas lasted way less time than expected.

Fair enough. You U-Haul example is reasonably compelling. I can see that being a real use case.

A large percentage of the population uses cruise control, probably without realizing that it's the single easiest thing you can do to increase your (freeway) mpg.

It's also apparently pretty common for hybrid-car drivers to adjust driving patterns to improve mpg, partly because the car gives rapid feedback - gamification in real life! - but there's probably also some selection bias, as people who buy high-mpg vehicles are more likely to be concerned about fuel efficiency.

Apple should have added a Amp or Watt usage number...

I want Activity Monitor to show how much battery each process is using.

It does. It's the "Energy" tab. It doesn't give you amperage or anything, but it tells you the "Energy Impact", which is a relative measurement of the current energy usage, and "Avg Energy Impact" which is the average for the app. Similarly, if you click on the battery menu, it will call out any processes that are using "significant" energy.

My bad. Thanks.

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