A local Bolt driver asked me to explain “What is the thin yellow or green line to the left of the estimated mileage?”
That thin line to the left of the Battery Gauge or Range Indicator is the “Trend Bar.”
The battery gauge and dash display has a number of features to help the driver maximize range by maximizing efficiency. The trend bar is one, albeit subtle, such aid.
I didn’t know what it was either for a long time–and I thought I’d read the manual thoroughly. It took a comment from Eric “1%” Way (NewsCoulomb) on a Bolt forum (the “trend bar”…?) about how to use the trend bar that I noticed it for the first time. Way characterized the trend bar as similar to the instantaneous mpg gauge on many conventional cars.
“Keep in mind,” writes Way, “the Bolt EV’s Range Estimator is always seeking equilibrium, so the longer you drive at a given efficiency, the more the trend bars will disappear and your middle range estimate will result from your recent driving efficiency. So really, the trend bars only show up when your driving efficiency becomes abnormal relative to the middle range estimate.”
Way knows what he’s talking about. He’s probably put more miles on a Bolt than anyone else and he freely shares his experiences driving electric on his YouTube channel.
The trend bar indicates “how recent driving habits, conditions, and climate settings are affecting the range prediction” in the battery gauge.
When the bar is below the midpoint of the gauge (yellow), you’re consuming more electricity than previously and your estimated range is optimistic. The unsaid message is “plan accordingly.”
When the bar is above the midpoint of the gauge (green), you’re consuming less electricity than previously and your estimated range is pessimistic. Or, you have more kWh to work with than the estimates reflect.
The trend bar is just another useful tool that skilled Bolt drivers use to maximize range when they need it.