It it like the e e cummings poem "she being Brand"? Because that's, you know, about a guy driving his new car for the first time.

That's clearly what that poem's about. I certainly don't see how it could be interpreted as a metaphor for anything else. If it were, though (which, as I say, it clearly isn't) I might be inclined to argue that horses are a more intriguing metaphor for whatever it's (hypothetically) (but obviously not really) metaphorically speaking about than cars are. But since it's just literally about a car you can hardly complain about that.