The romantic car chase comedy (yes, it really is!) Hit & Run, from writer/director/star Dax Shepard, tells the story of Charlie Bronson (Shepard), a nice guy with a questionable past who decides to leave the witness protection program to ensure that his fiancée, Annie Bean (played by real-life fiancée Kristen Bell), can accept a once-in-a-lifetime opportunity in Los Angeles. But, their road trip grows increasingly complicated when they are chased by the gangster friends (led by Bradley Cooper) that Charlie was trying to leave behind.

At the film’s press day, Dax Shepard and Kristen Bell spoke to Collider for this exclusive interview about how the movie came about, when they realized that it was actually a romantic car chase movie, translating their love for each other to the big screen, and how sincere the characters are no matter how outrageous the situations. Shepard also talked about his next directorial effort, Send Lawyers, Guns and Money, which he hopes to shoot next year, and what fans can expect from the upcoming season of his hit NBC drama series Parenthood, while Bell talked about what a dream come true it is to do the voice work and original songs for the Disney animated feature Frozen, as well as how excited she is to return to her Showtime comedy series House of Lies. Check out what they had to say after the jump.

Collider: Dax, was there a moment that you had to go from telling people that you were going to do a car chase movie to actually having to do a car chase movie?

DAX SHEPARD: That’s exactly what happened. We were doing press for a movie that David Palmer, Nate [Tuck] and I made, called Brother’s Justice, and they invariably asked us what we were going to do next and I kept saying, “A car chase movie.” And then, our friend Andrew Panay, who produced Wedding Crashers, finally said, “Hey, aren’t you guys doing a car chase movie? I think I have someone that wants to make it.” And then, I had to actually come up with what the car chase movie was. So, I went away and wrote it, and then we shot it. It all happened within a couple months. It was a very, very fast process.

Was there a point when you realized you were actually making a romantic car chase movie?

KRISTEN BELL: Not until the test screenings.

SHEPARD: Well, I knew I was making an honest [relationship movie]. But, I wouldn’t have guessed that females would have liked it the most.

BELL: From my perspective, we didn’t know the female response until the first couple test screenings. The people that stayed after to effusively gush were the women. The people that raised their hands during the Q&A were the women. They were all talking in the context of the relationship and the romantic writing.

SHEPARD: I was just putting my theories on things down, and I didn’t realize that any woman, other than Kristen, desired to be spoken to that way. I didn’t have that awareness, per se, when writing it or shooting it.

BELL: He wasn’t doing it to impress anyone.

SHEPARD: It wasn’t calculated. I wasn’t aware of it, I guess.

BELL: But, it was very interesting that the first hands up weren’t about any of the things that we thought the movie was about. It was a high response from women saying that they emotionally connected to these characters.

There’s something so sweet about the love that you guys have for each other. Were there challenges in having that translate genuinely, on screen?

BELL: We forgot the cameras pretty easily.

SHEPARD: It wasn’t hard, at all. We’re both actors and we’re in front of the camera a lot. We’re both on TV shows, which puts you in front of a camera, non-stop, so we’re good at blocking that out. And we have a real fucking rapport with one another, so it’s not hard to look at each other and lock into that.

BELL: You also strive to have this much comfort with your pretend significant other when you’re on camera, and we actually have it. So, there was a sincerity that I don’t think I’ve ever had on camera before, when I was with him. I was really being 100% natural.

Dax, when you were writing these characters, were you conscious of how sincere they were, no matter how outrageous the situations?

SHEPARD: I was. The commitment was, “Okay, I’m going to put all these people in really insane situations and have these crazy events happen, but I want everyone’s response to be very human, very grounded, very real and very flawed.” So, I was aware of that part. Tom Arnold’s van drives away from him, but it immediately turns into a very emotional exchange. I do recognize that he’s super embarrassed and I try to comfort him, but now he’s so embarrassed that it’s hard to get him back. What interests me about a van driving away is, “How do we get down to the really funny, emotional stuff that would be going on, as a result of that?”

Kristen, what was it like to watch Dax where so many hats with this? Was there ever anything that you had to reassure him with, or did he just have it all under control?

BELL: The answer to both of those questions is actually yes. I felt completely confident in his capabilities, but he also tends to, every so often, get a little fatalistic, and I am eternally optimistic. That’s why we make a good pair. So, if I sensed it – which you can do with your significant other, if you’re in tune with them – I would often overwhelm him with optimism and a better outlook and reassurance. But, for the most part, I just sat and watched him work and smiled with pride.

SHEPARD: Kristen has a very healthy perspective on things. I’ll get way more worried about what the end product is going to be, or if I’m going to deliver, and she would constantly be like, “You can’t fuck this up. You’re going to be with your friends, hanging out for six weeks straight. You’re going to win, regardless. There is no bad outcome with this, as long as you’re with all of us, having a good time.” And I was like, “Yes, you’re right.” If I could just focus on that, it would definitely take the pressure off.

Dax, when the words on the page are yours, do you find yourself more strict about wanting the actors to stick to them, as opposed to being the actor playing around with somebody else’s words?

SHEPARD: Sure, to a degree, but that wasn’t even the driving force for why this movie wasn’t very improvised. Our issue was time. We had no time. Even when improv is encouraged, you get what’s on the page done perfectly, and then you start loosening it up and playing around. We didn’t have the extra takes to play around with. If we got something perfect, it was time to run to the next set-up and shoot the next scene because we had so little time. So, it was just a practical thing, that we didn’t really horse around too much.

Do you already know what you’re going to be doing next, as a director?

SHEPARD: Yeah, I wrote another movie in April, called Send Lawyers, Guns and Money, that’s a little bit more aggressive and a little darker. It has more action and more explosions, but the same level of emotional chit-chat during the explosions.

BELL: We hope to shoot that next year.

Kristen, have you gotten to record any of your voice work yet for the Disney animated feature, Frozen?

BELL: I have, yeah!

What’s it like to be a part of a Disney fairy tale? Is that just a dream come true?

BELL: It’s so dreamy! It really is, more than anything, a dream come true. I can remember being six years old and watching Sleeping Beauty or Aladdin or The Little Mermaid. I saw Pocahontas and desperately wanting to be Judy Kuhn. I wanted so badly to be a Disney princess, but also be able to sing that role. There’s such a sense of quality. Those Disney cartoons are so consistent. So, I have recorded all of the dialogue and some of the songs. They’re still being written by the Lopez’s (Robert and Kristen), who wrote The Book of Mormon, and they’re exceptional songwriters. They work really fast and with a high level of quality. It’s been such a treat.

SHEPARD: That’s been a professed dream since I met her. This isn’t something that she retrofitted to be like, “Oh, I always wanted to do this!” She’s legit. She always talks about this.

What can you say about the upcoming seasons of your TV shows, House of Lies and Parenthood?

BELL: I don’t know ‘cause they’re just being written right now. We go back in October, but I’m so excited to go back to that family. I’ve missed them so much.

SHEPARD: And we’ve finished Episode 3. Jasmine and Crosby are married, and you’re seeing our first year of marriage and all the trials and tribulations.

Would either of you like to guest star on each other’s show?

SHEPARD: Yeah, why not? It sounds like another paycheck to me!

BELL: Sure! We love working together, so absolutely!

SHEPARD: There was talk of Bell being who Crosby cheated on Jasmine with in Season 2.

BELL: But then, he found out that Minka Kelly was also a contender, and I lost the job

SHEPARD: That was way better idea! No, they wanted it to screw up the family matters with Adam (Peter Krause) because they were so dependent on Gabby (Minka Kelly), as a behavioral therapist. They wanted it to have a lot of fall-out. And it was Minka Kelly!

Why do you think it is that you guys work so well together, when it’s been so disastrous for some couples?

SHEPARD: I don’t have an answer for that. We don’t know why we’re anything. We’re just two normal human beings that have jobs that make us popular, but we don’t think of ourselves as being unique. We’re just two people in a relationship.

BELL: We’re not doing anything exceptionally. We’re very communicative. That’s probably the only thing we know that helps us.

SHEPARD: We have sex, yearly. We do that annually. We commit to that.

BELL: Yeah. But other than that, there’s no secrets.

SHEPARD: Well, there is one secret. I was reading Blink, by Malcolm Gladwell, and there is a chapter in there about a guy who studies couples, and he can predict, with 98% accuracy, who will get divorced by watching them communicate. And the number one key ingredient to a divorce is contempt, so we put a lot of energy into making sure we don’t ever have contempt for one another. We’re just irritated, in that moment for that thing, but Kristen is not permanently any given attribute. She’s just currently being a raving and raging bitch.

BELL: Irritation and anger is fine. Contempt is not. It’s more, “Kristen is acting crazy, or acting like a bitch. She’s not a bitch, or a crazy.” When you start to think about it, there really is a difference there.

SHEPARD: Yeah, a huge difference. We don’t roll our eyes at each other.