The Joe Biden administration recently proposed a rule to continue its crackdown on so-called “junk fees” by imposing penalties on the companies that don’t show full prices up front.

The rental car industry has its own share of those add-on fees. Some are taxes imposed by local governments and some are optional, but the result is the same: The fees make it difficult for consumers to know the full price of their rental until they’re paying the bill.

Emily Stewart, a senior correspondent at Vox, has had her share of bad car rental experiences. She recently wrote about how rental car fees can be deceptive.

“I think it’s fair to say it would be much better for consumers to just know how much everything was going to cost us right off the bat,” Stewart said. “I don’t want to have to do math and go back and guess how much everything might be.”

“Marketplace” host Kimberly Adams talked with Emily Stewart about the rental car experience and how difficult it can be to navigate. Below is an edited transcript of their conversation.

Kimberly Adams So rental cars. What made you want to write about this?

Emily Stewart: To be honest, this is one that I hear about all the time from readers and from people in my life. And I hear about it from myself. I have never had a rental car experience that has been smooth.

Adams: Was there a specific incident that made you say, “This is the time I’m going to dig into this?”

Stewart: A family friend actually just rented a car out in Denver and was looking at their receipt. And they were like, “What in the world is going on?” The price of the rental car had basically doubled with all of the fees. They sent me over their receipt, and just kind of bit by bit, I started to look at what each one was. And I was honestly pretty surprised at what I found, because I think we really don’t know how rental car fees work in a way that maybe we are a little bit more accustomed to on tickets or flights.

Adams: What are some of the fees that really jumped out to you as you were doing this reporting?

Stewart: So I think it’s important to point out that a lot of these fees are from state and local governments across the country. It is not popular for policymakers to raise taxes on their residents. It’s a lot easier to raise taxes on tourist or travelers. And so you will see all sorts of fees for highways or just random taxes that you don’t quite understand. If a rental car agency is at an airport, the airport will charge that rental car agency money. That money gets charged to you. And then, of course, there are all the fees that show up once you’re at the counter at the airport, trying to figure out what to do. Do you want extra car insurance? Or do you want to fill up gas on your own? Or do you want us to fill up gas for you? Do you need a car seat? So there are all sorts of different fees that show up. Some of them are things you can’t avoid. Some of them are things that you can.

Adams: Why aren’t these fees and taxes included in the base rate?

Stewart: That’s, I think, the million-dollar question. I think right now, you know, at least rental car companies will tell you to a certain extent that they want to disclose this stuff, right? Like, they also don’t want to take the blame for all these fees, that some of them really have nothing to do with them. They cannot tell the state of California or whatever that they’re not going to charge these taxes. But at the same time, I think it’s fair to say it would be much better for consumers to just know how much everything was going to cost us right off the bat. I don’t want to have to do math and go back and guess how much everything might be.

Adams: So after doing all this reporting, what tips do you have for the rest of us when it comes to renting a car?

Stewart: It’s good to think about before you get to the counter — I think a lot about a few years ago, I was in Madison, Wisconsin, and I was not prepared to answer the insurance question, and at some point wound up in a back and forth with the agent over whether I thought a tree might fall on my car and I needed that kind of insurance. So I think it’s a good idea to go in and know how to answer that insurance question. But I think a lot of it really is trying to comparison shop and then just really doing your homework, which isn’t the ideal answer, but it’s kind of the best one we have for now.

Adams: How do you feel now when you walk up to the rental counter?

Stewart: Last time I rented a car was fairly smooth until I got to the parking lot. The first two cars I got didn’t work. The first one, the battery was dead. The second one had somebody else’s luggage in it. I feel bad because I understand it is a hard industry, right? Somebody picks up a very big-ticket item from you, and you don’t know where they go with it. But at the same time, even after I published this story, the amount of emails that I’ve gotten from readers with different horror stories has made me feel like I was onto something, at least a little bit.