The unsung Buick LaCrosse was completely updated last year and comes with a 3.6L V6 that has been modernized with fuel injection and cylinder deactivation. Despite its 310 horsepower, this sedan remains very fuel efficient, thanks in large part to its nine-speed automatic gearbox. A 2.5L four-cylinder eAssist (hybrid) powertrain, which includes a 27-horsepower electric motor and a six-speed automatic rounds out the lineup.