Even people who never watched the original run of Dallas probably know that one of the series’ major plotlines can be summed up in three simple words: “Who shot J.R.?” In the final moments of the show’s third season finale, J.R. Ewing (Larry Hagman), the show’s scheming villain but also arguably its central character, was seen getting shot by an offscreen assailant. In the Nov. 21, 1980, episode “Who Done It,” viewers finally learned that it was Kristin Shepard (Mary Crosby), J.R.’s mistress and the sister of J.R.’s wife, Sue Ellen (Linda Gray), who shot J.R. and framed Sue Ellen for it. She didn’t go to jail. No, mere moments after Sue Allen outed her as the shooter, Kristin announced that she was pregnant with J.R.’s baby. The character eventually drowned in the Southfork Ranch pool. J.R. Ewing was also famous for the cars he drove in the show, he favored the three pointed star.
Mercedes-Benz W116: The 280SE J.R Ewing drives at the time the series started in 1978 is totally with the times. It may have been strangled by emissions add-ons in the wake of the first oil crisis, but the W116 was always an intimidating brute. Dictators rode in them, so it made sense the villain of the show – someone in Texas and in oil – would have one too. But then he got a 450SEL and the gas-guzzling giant finally had some power to go belting on those completely straight and flat Texas highways.
Mercedes-Benz W126: As the series progressed into the '80s, J.R. had to step up his game and got a new 380SEL.
Mercedes-Benz W140: For the first TV movie, J.R. Returns, they went back to giving J.R. his big, silver Benz. By the time it aired in 1996, this was a S420 W140. (Source - Zac Estrada - jalopnik)