and Detroit Diesel. When GMC launched the Twin Six V12 in 1961, it wanted to prove that gas engines could stand up to diesel mills in the heavy-duty segment — and, in some ways, it did with its ...

However, the last V12 ever fitted to a series production passenger car was ... So, the GMC Twin Six debuted in 1960 poised to take on the new diesel threat with a healthy dose of iron-clad Detroit ...