Yes and no. I'm the same way, and I have terrible anxiety about it becuase I know it's not going to go well. I'm militant about DS's routine for bedtime, and he seldom naps well or sleeps outside his crib.
For us, napping in the car isn't the preference, but we do it because we just need to sometimes. It's not the best solution, but it works when you just can't rearrange your day around nap.
We're travelling next weekend and he'll have to sleep in the pack n play. I KNOW that's not going to go well. We've created a monster, where we've NEVER slept in the same room as him. Works great for home - no issues with putting himself to sleep, etc... - but can be problematic for travelling.
You should chill out about the scared/crying bit. If you're around, she'll be fine. You're there to comfort her as needed. And you know that she's going to have to cry to get to sleep.
Everyone else is right. The more you do it, the more she'll be used to it. But do what works for you.