indicators

I am sure this has come up before but what in the world is the hidden, glow plugs idiot light on the Volt instrument cluster for??? Is this an oversight from the engineers having scrapped a diesel variant? Or is it simply used as an indicator during service procedures or something? Very...

I am a new Volt owner. Previous owner of Leaf with NavTraffic, so very familiar with how NavTraffic should opearte. (BTW - loved the Leaf, but tired of the range anxiety). I am having an issue with the traffic indicators (Green, Yellow, Red lines) disappearing at lower (zoomed-out)...