There's a transcript below too, though if you don't have speaker you're missing all the fun.
De Niro: Look at the size of that trunk, you can put three bodies in there
De Niro: Just kidding, just trying to levitate the situation
Customer: Ok thank you, we appreciate it
De Niro: Sure, sure, what kind of car you used to dive
De Niro: It's like a Toyota
Customer: It's a Lexus
De Niro: Toyota Lexus same thing ... Japanese right. Anyway, let's get serious, you want to buy this car or what?
Customer: I don't know, we have to think about it
De Niro: What's to think about it, you told me you like it, you asked me 10000 questions about it and I answered every single one of them, you drove it, you love it, what more do you need to know?
Customer: Well you know it's a lot of money, and we just need the time to consider it
De Niro: Well why don't you consider this, you've been breaking my balls for about one hour asking me about every accessory on this car "What about the light, what about this..."
Customer: You cannot talk to customers like that
De Niro: You're not customers as far as I'm concerned, you wanna buy this car or not?
Customer: Not from you, I wanna see the manager
De Niro: You wanna see the manager, I'll show you the manager, here's the manager [grabs his things], you wanna talk to him...