The mild-hybrid eAssist powertrain becomes the standard powertrain for the three lower trim levels. The turbocharged 2.0-liter engine remains an option. Other upgrades include the standard IntelliLink electronics interface that brings with it smartphone integration technology. Turbo models get a standard heated steering wheel.

Going head to head with the world's best sport sedans is no small undertaking. Yet that's the goal for the 2013 Buick Regal. This midsize sedan's performance doesn't hit its mark, yet the Regal does have some good qualities that get your attention.

The story of the Regal really revolves around its engines. The Regal starts out with a 2.4-liter engine backed up by a mild hybrid system ("eAssist"), which has become familiar as a simple stop-start system for the engine. This boosts city fuel economy to a useful 25 mpg, while the 36 mpg achieved by this engine in highway mode makes the Regal superior to every other midsize sedan, though the acceleration definitely doesn't do anything for the car's personality.

The midgrade 2.0-liter turbocharged engine is a step up and still delivers good fuel economy, yet the acceleration is still underwhelming. It's only when you step up to the performance-oriented GS model and its 270-horsepower turbocharged engine, sport-tuned suspension and Brembo brakes that you get a sedan that prioritizes driving involvement.