The morning after he murders a man by tearing out his throat with his bare hands, Dalton parks his car. This is the way of things. Extraordinary events are rendered extraordinary by their singular, instantial nature; and even in Jasper, tomorrow is another day. Dalton has things to do on this bright sunny day, with the famous hills of Missouri visible in the distance, and having murdered a man by tearing out his throat with his bare hands the night before does not change that. So Dalton goes about his business, and to do his business he must needs park his car at his place of business. It’s as simple as that.
Less simple, more purposeful, is the message communicated by his choice of car. Note that Dalton is no longer driving the shit-brown beater he picked up from Big “T” (one of the Four Car Salesmen) earlier in the film—the kind of car he uses while working a gig because it’s cheap and more or less disposable. Rather, he’s back in the Mercedes-Benz with New York plates he used to drive from New York to Missouri in the first place—his real car, the car he keeps hidden in a parking garage or under a tarp, the car he spends his mid six-figure yearly salary on. His off-duty car.
You realize what this means, don’t you?