The previous version of the Mazda 6 did not give U.S. buyers a diesel option, and the 2014 model will be one of only two midsize sedans available with a diesel engine stateside, the other being the Volkswagen Passat.

FORBES: Mazda Bets Big On Diesel With The All-New 2014 Mazda 6

Cummins' bread-and-butter N14 diesel engine was basically a 1970s model with lots of tweaks.

FORBES: This time is different -- maybe