Which they did in order to show the obvious problem in a safe and entertaining way. It doesn't matter if the battery was going to die in 10 more miles, or 40 more miles on a highway. It would be just as inconvenient and less safe.
"ignoring all of the warnings, and by concealing from viewers that they were ignoring all of the warnings"
What warnings did they conceal? They were talking to each other over radios about how their cars said they were almost out of juice.