Though automakers like Stellantis, Mazda, BMW, and Mercedes-Benz are keeping a few straight-six engines alive in 2025, there are currently just two straight-six diesel powerplants left on the market.

Oh, Pontiac, your death in 2009 was a bitter pill, as memories of big block Trans Ams and GTOs flooded forth with the tears. Not that Pontiac's end was hard to see coming; the brand had been ...