As I understand it, the 'bells and whistles' in her car is for the family, and the family rarely ever rides in his vehicle, so who are the bells and whistles for?

What are the bells and whistles she is objecting to? You don't need to answer me here, I am not the judge of which are right for you, just think about what exactly she is objecting to, why she objects, and why you are fighting her on it.

She may not want you to be in attention-getting vehicle. What's wrong with that?

Marriage is the triumph of imagination over intelligence. Second marriage is the triumph of hope over experience.
(Oscar Wilde)