The 25-year-old model-and-actor is good pals with the 'Wolf of Wall Street' actress but after seeing her in the film, before they had met, Cara wasn't sure if the 27-year-old actress would be someone who she might be friends with.
She said: ''Someone I really didn't think would be the way they were, was Margot Robbie.
''I'd seen her in 'Wolf of Wall Street', and I don't like to make judgements on people at all, but I didn't assume that she would be the most incredible, down to earth, hysterically funny bro in the world. Like literally, would kick it with her 24/7 forever.
''She's the biggest babe, so sweet, uber-talented and has so many dimensions to her.''
Cara would love to be her 'Suicide Squad' co-star's side-kick if the pair were both superheroes in real life, but she would like to see her fellow catwalk star Adwoa Aboah become Prime Minister one day because the 25-year-old model would be a great inspiration for women.
She said: ''She's very organised. She's quite late though - sorry Adwoa. I say that because usually I'm late, but I turned up to a shoot a tiny bit before her recently and I literally sat their gloating.''
Cara insists she is ''happy'' if one of her friends beats her to an acting job, because she doesn't want to encourage competition between women.
Speaking to ELLE magazine, she added: ''That kind of attitude, competing, is a very male thing to do. It's an aggressive way to look at life and I think it's been placed on women. I don't think it's women's natural nature to compete at all.
''For women, it's about the space we've been given. Because, historically, there's only been space for one. It's bulls**t, but that is literally what it has been.
''As more space is being allowed, the less women need to compete. At least four of my friends are actresses and we've gone for the same jobs and I am so happy if one of them gets the job.''