I think they mean if you are sitting in line for an hour or more waiting to get gasoline that you will waste a lot of gasoline just sitting there running the engine.
It’s possible I was thinking too boolean. Here is what it said...
“When you sit in your car and idle, and you have the heat going, you actually burn quite a bit of fuel.”
The predicate “and you have the heat going” implies that if you did not have the heat going then it may not burn quite a bit of fuel.
Most likely residual grumpiness from last Tuesday on my part.