[Goose]

Well,
After much pondering, I've decided that the car will have only one roll bar; especially since a second one can always be retrofitted at a later date if we so desire.

I don't plan to drive the car like an idiot (mostly interested in cruising) so, barring any unusual circumstances, I don't foresee that the car will be in a rollover situation where the roll bar will be needed. Also, I have yet to hear about anyone being killed due to the lack of a headrest in a rear end collision and, for now, will take my chances.

In the end, I think it's still safer than a motorcycle.

Thanks to all for the comments and opinions.