Your Gas Gauge as User Experience | Hacker News Reader

Your Gas Gauge as User Experience

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27 pointsjeffclark23 comments

As far as user experience goes, having a non-linear gas gauge is, for me at least, infuriating. My 94 Accord had a fairly linear gas gauge, I knew that when I got to 1/4, there was roughly 1/4 tank of gas left. Now, in my new Mazda 6, there's a definite non-linear effect, and have been surprised more than once by how little distance I get out of that last "1/4 tank."

I find it somewhat dangerous to have a non-linear gas gauge, especially at the bottom end if you're not used to it. Let's say I just drove 150km and used a 1/2 tank of gas, then I see a gas station and a sign that says that the next gas station is in 100km. Given that I've got a 1/2 tank left, I should have 1/6 of a tank to spare when I get there right? Well, no, turns out that it's cutting it really close. My gas light goes on when I'm about 10km away from the gas station. Not a pleasant experience at all.

I'm seriously considering doing some math can hooking up some sort of microcontroller to the gas gauge to undo the "calibration" done at the factory. Really wish there was some kind of bolt-in mod for this.

What I do is to ignore the gas gauge completely. I keep track of the miles driven. My driving is fairly consistent, and I know the rated capacity of my fuel tank, so I can fairly easily determine when I should fill up based on how many miles I have driven.

I like your style. However, this can be a problem when you're switching between city and highway driving. My vehicle gets 1.5x the mileage (300 miles vs 200) on a full tank when I drive on highways as opposed to in a city. So it is helpful to have a sense of what the gas gauge is telling you.

Yeah, I just assume city driving in my mileage calculations. That way, I have a little extra safety factor when doing highway driving.

300 miles? The tank in my 1.6 VW Golf is 55 litres (12 imperial gallons) and I get between 420 and 500 miles out of a full tank (I get around 37mpg combined and 42mpg on highways). Do your cars generally use more fuel than European cars? Do automatic cars really affect the gas usage /that/ much?

I drive a monstrosity.

I don't grasp the benefit of this approach. You have a gauge that (albeit not particularly accurately) tells you how much fuel you have left, and in doing so, gives you a clue as to when to fill up.

It would be like working out how much to pay for heating by remembering how warm you keep your house, and how good your insulation is. Why not just look in the little cupboard and get the number off the meter?

This isn't rocket science. My Audi (and BMW before that) have nice clean digital displays of predicted miles remaining based on driving history, tank capacity, and measured fuel consumption. Turns out 'How far can I go?' is a better metric than 'About how much of a tank is left?'.

Even then, the estimated remaining mileage in your gas tank is also fudged. A few seasons ago Top Gear had Clarkson drive some sort of Audi - he drove it until the indicator showed he had 0 miles left, and he kept going for a surprising while longer (he never did run out of gas). Given that evidence, I'm reasonably sure that car makers also factor in a safety margin so customers' cars don't immediately halt when the mileage-remaining indicator hits 0.

My 2010 MINI (BMW-made) has the same deal, and you could use the stats it gives you (kilometres until empty, average kilometres/litre, and actual tank size in litres) to calculate what's left in your tank, but why not just add it to the displays that already exist?

I also notice European cars (Audi, BMW, MINI, Saab, even VW etc.) tend to be more accurate and linear than American/Japanese vehicles. But that's just me.

When I was a kid my family had a Mercedes diesel and my aunt had a Cadillac. I remember noting that the Mercedes fuel gauge was labeled "Tank" and marked off in a round arc with equal distances between each of the markings. The Cadillac had a square gauge labeled "Fuel Data Centre" with a needle sweeping across markings in a straight line. The Mercedes was much more practical.

The pinnacle of gas gauge experience has to be the Toyota Prius. The article was interesting, but I was a bit bummed to see no reference to my favorite driving experience.

Here's an the Prius's in-dash energy monitor: http://www.youtube.com/watch?v=dqP_eS_f1qY

The Honda CR-Z has trees which lose their leaves if you drive inefficiently, and you have to drive really carefully to get them to grow back.

The Honda CR-Z is a great car, it's too bad so much focus is paid to 0-60 times.

I think it's a really innovative blend of driver involvement, education about efficient driving, and sporty driving dynamics. A really cool "hack" of a car.

Reminds me of the problems Transmeta had with their low-power processors. The laptops made with them had like 8-hour battery life, but at that time, everyone was looking at performance benchmarks and thought they were crap. Intel bought them and later used a bunch of their tech in mobile processors. I think people will eventually learn to appreciate good mileage, but the first 5 years or so will be pretty rough in the market.

On the other hand, the "full reserve" is handy when you need to return a rental with a "full" tank of gas.

Or un-handy not, when it turns out that the last bastard to use the car left it two gallons from full.

In a car rental context it's basically a transfer of wealth from the honest to the dishonest.

It's less a case of dishonesty than it is that airports (the usual place for car rentals) are a bit out of the way and often have uncompetitive fuel prices.

Yeah, I'll generally fuel up a few miles from the airport, but not fifty miles from the airport. As long as everyone has a similar idea of what's acceptable it works out fine.

The gas gauge is just another 'idiot light' to me. It doesn't really tell me anything reliable but it does spur further action. Similar to how a maintenance required light lets me know I need to plug in the code reader and check it out. When the gauge indicates low, I'll pay attention to how much mileage I'm expecting and then time the next fill-up around that.

(Tracking mileage is done on my phone. Using the data stored there I can accurately gauge how many miles I can get using the odometer. I've done this for the entire life of my truck and I can peg a 3500 mile roadtrip's cost within 5$)

That said - I feel that I would prefer an accurate reading on the tank status through the gauge to be standard. I wouldn't feel so uncertain when driving someone else car past the last gas station for 50m en route to Vegas.

I came across an interesting illustration of some calibration taking place a couple of years ago. To cut a long story shut, I lifted up the hood/bonnet and was dismayed to see petrol spewing everywhere from a leak in one of the hoses supplying the inlet manifold.

At this point I'd noticed that the petrol gauge was reading around an eight of a tank left. I fitted a replacement hose, and the gauge shot up to over 1/2 a tank! This happened about two years ago in a '92 BMW E36 325, and I can only guess at what the ECU was interpreting from all of this...

There are similar UX concerns for progress bars. Users will perceive an operation as taking less time if the progress bar accelerates (i.e. the last half takes less time than the first half) than if it decelerates, regardless of actual time taken. This was an annoying problem with file copying in Vista where the typical behavior was to progress along to close to 100% then hang there for a while, which people hate experiencing.

This article is impeccable -- I have consciously observed every effect noted in the article on my 97 Ford Explorer.

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