We've all seen Marv's Blue Falcon on the road. It's that car that's so beat up and worn down that it just looks old, in addition to smelling like fuel and exhaust at all times. And in Marv's case, let's also add the fact that it's not reliable and doesn't start properly into the mix. In other words, through and through, this car is junk. And yet Marv adores the car and won't hear a word from anyone who says otherwise. Why? He bought it to take Suzanne out on the town:
Originally he bought that s***box car to go and look for her, but he didn't even make it out of town. The world was too big, I think, and Marv gave up. That was when he became extra tight and argumentative. (1.5.14)
Okay, okay, we'll give the guy a break. The Blue Falcon is a symbol of what Marv wanted from his life and how he pictured it to be. He thought he'd wine and dine Suzanne and live it up in his car (since he's the only one of his friends who even has one), but things went topsy-turvy when she got pregnant and jumped town. The car is a reminder to Marv of what he had, and how he can't control what's ahead.
Just like Marv says when the cop teases him about the car, he's got his reasons for keeping it. We think everyone assumed his reasons were money-based, but it turns out they're more emotional than we ever would have guessed.