My theory, (and this comes from doing some aftermarket work for gypsies dealers) is as follows:
"Hal knew this was his last day at Jack Sampson Dodge. "Number 4 in the Southwest!" went the idiotic slogan... There was no way he would continue working for the man he caught half-naked with his wife at the annual Christmas party. They were too preoccupied to notice Hal enter the coatroom at the Elk's club, which meant Hal would still have access to the dealership's IBM corporate ordering terminal.
He used his key and came in early the next day. Jack and the rest of the staff, despite their huge tolerance for alcohol, would still be nursing hangovers from the Christmas bender. What could he create as a nice F-U to the boss man?
"Hmm, let's start by ordering a musclecar-shade of piss-yellow on the type of 4dr sedan normally purchased by grandmothers and driving instructors. Haha, that will screw the ol' sumbitch". But then it occurred to Hal... What if that SOB ran it through the bodyshop and painted it a sensible shade of dark metallic green? Those guys are on the payroll, and that scumbag would just add the paint to an insurance job. "No, I better really F this up..."
"How about a big-block and manual brakes?" A smile came to Hal's face. "Let's add the 5 speaker cassette option, but play it through an AM radio." Still missing something. "How about a black interior and no A/C. Have fun selling that when it's still here in July you fat prick!"
With the order submitted and verified, Hal walked out of the sales office and noticed his secretary was looking rather pretty this morning. She didn't attend last night's booze-fest. Maria had been many things, but mostly a good secretary to him. He approached her and said, "I never really noticed how sweet you are to me. It just so happens I'm free this morning, would you like to go to Denny's with me?" She accepted and the two walked through the lot to Hal's Winchester Gray 1971 New Yorker Coupe. It was a particularly beautiful morning, so much that Hal opened the sunroof, casting a perfect light on Maria's tanned, long, shapley legs.
Hal and Maria never returned. It's rumored they started a new life together. And the Dodge? It arrived a month later. Jack's string of profanity is rumored to still echo through the showroom of the dealership, almost 50 years after the fact.