Your Gas Gauge as User Experience

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."<p>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.<p>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.

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?'.

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.<p>Here's an the Prius's in-dash energy monitor: <a href="http://www.youtube.com/watch?v=dqP_eS_f1qY" rel="nofollow">http://www.youtube.com/watch?v=dqP_eS_f1qY</a>

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

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.<p>(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$)<p>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.<p>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.