Range remaining indicator

by Ernie Hernandez on February 3, 2012

LEAF range remaining indicatorHow much do they fluctuate in internal combustion engine vehicles?

Today we were driving our internal combustion engine (ICE) powered vehicle when we noticed the range remaining indicator blinking at us. Having seen this many times before we were not concerned at all because we know that there is a significant reserve of gasoline in the tank after it goes to zero (we live life on the edge). But it did get us thinking. How might the behavior of a range remaining indicator in an ICE powered vehicle compare to the one in the LEAF? So we did a real-world analysis on the spot.

After our last errand, which consisted of low speed city driving including stop signs and traffic lights, the range remaining indicator indicated 19 miles remaining. Pulling onto the freeway, which in an ICE vehicle offers better fuel economy than city driving, the range remaining indicator climbed up to 25 miles remaining. At this point we were cruising along at a steady 65 miles per hour with only minor elevation changes. When it dropped to 24 miles remaining we dropped our speed to about 57 miles per hour. Our range remaining indicator dutifully started climbing until it reached about 31 miles remaining. We are now about five miles into our drive that started out with 19 miles remaining. When it dropped to 3o miles remaining, we dropped our speed slightly, but did not want to be driving under 55 miles per hour on the freeway and saw two more miles drop off slowly over the next few minutes.

Almost home. Just a couple more miles. So what did we do? Accelerated up to 70 miles per hour to see the result. In about one mile our range remaining indicator went from 28 miles to 18 miles remaining. We exited the freeway and pulled into the gas station at the corner and proceeded to put in over $66 worth of gasoline at $3.79 9/10 for every gallon of regular gasoline. Premium was priced at $3.99 (which thankfully we don’t need). Mid-grade was $3.89. We average about 29 miles per gallon in this vehicle overall, so that $60 took us about 500 miles. That would be roughly 8.33 miles for every dollar spent on fuel. In our LEAF we get about 40 miles for every dollar spent on fuel. In other words, to cover that same distance would have cost about $12.50 in our LEAF. Now you know why many LEAF drivers are smiling as they’re driving down the road.

But let’s get back to the volatility of the range remaining indicator. Many have commented at how sensitive the indicator seems to be in the LEAF – it seems to move up and down with every little variation in speed, driving style and terrain variation. Guess what – it’s doing its job! You see the same behavior in the ICE powered vehicle’s range remaining indicator, as we have just observed. Most people have never seen this because they fill their car up prior to activating this indicator (these indicators typically come on automatically when running low on fuel. Also, it can usually be selected by the driver). I would say that some people probably don’t even know that their car has a range remaining indicator because they fill up at a quarter tank or more.

We have written before that we ignore the mileage remaining indicator and purely rely on the bars to the right of the number indicated. In the photograph at the top of this post (taken at the end of day one of the ownership of our LEAF), we show four bars remaining. If you allow yourself 6 miles for every bar, you will likely be just fine. If it’s really cold and you are using the heater and have significant terrain changes you can use 5 miles per bar to be really conservative. Now go out and have fun in your electric car.

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