For decades, the gold standard brand for a straight-six-cylinder-powered sport sedan has been BMW. But the gold standard doesn't necessarily mean being the only general game in town worth considering.

The straight-six engine is making a resurgence. BMW has always carried the straight-six torch, though the likes of Nissan, Volvo, and Mercedes-Benz all have historical inline-six connections, too.

Cars that share major internal components are often similar and in the same vehicle class. However, there are plenty of cars out there that share an engine despite offering completely different ...