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.

There are some bright spots, including plenty of standard equipment and an attractive cabin. Nevertheless, the 2013 Buick Regal is outshined by competitors such as the Audi A4, BMW 328i and Volvo S60. A better comparison can be found in the smaller Buick Verano and more modern Buick LaCrosse, which are very impressive American-style sedans.

The 2013 Buick Regal comes in two basic trim levels: base and Turbo. Each of these trim levels is eligible for different Premium option groups. The high-performance GS stands by itself.

The base Regal comes well-equipped with standard features that include 17-inch alloy wheels, automatic headlights, foglights, heated mirrors, keyless entry, cruise control, dual-zone automatic climate control, leather upholstery, heated front seats, an eight-way power driver seat (with four-way power lumbar), a power height-adjustable passenger seat, split-folding rear seats, a tilt-and-telescoping steering wheel and an auto-dimming rearview mirror. Also standard are a customizable touchscreen interface, Bluetooth phone and audio connectivity, OnStar emergency communications, and a seven-speaker audio system with a CD player, satellite radio, an auxiliary audio jack, an iPod/USB audio interface and IntelliLink smartphone integration.

The Premium 1 Group adds rear parking sensors, keyless entry/ignition, remote ignition and an eight-way power passenger seat (with four-way power lumbar). Moving up to the Premium 2 trim level gets you xenon headlights, rear-seat side airbags and a nine-speaker Harman Kardon surround-sound audio system.

The Turbo versions of these two Groups add 18-inch wheels and a heated steering wheel along with unique powertrain components. The Premium 3 is a Turbo-only trim and gets 19-inch alloy wheels, an adaptive suspension and adjustable driving settings.

The top-of-the-line GS includes those items plus a more powerful turbocharged engine, sport-tuned suspension, Brembo brakes, front parking sensors, unique exterior and interior accents, front sport seats, a thick-rimmed three-spoke steering wheel and a version of the Interactive Drive Control system modified for sportier driving. The Regal GS can also be had with optional 20-inch wheels with summer performance tires.

Other options available across the lineup include a sunroof and a navigation system (not available on base and Premium 1 models).

The 2013 Buick Regal is now offered with a choice of three different powertrains. The new base engine is a 2.4-liter four-cylinder with "eAssist," a mild hybrid technology. This engine puts out 182 hp and 172 pound-feet of torque. A six-speed automatic with manual shift control is standard. EPA fuel economy estimates for this powertrain are 25 city/36 highway and 29 combined.

The Turbo models get a turbocharged 2.0-liter four-cylinder good for 220 hp and 260 lb-ft (also available on lower trim levels). The six-speed automatic is standard, but a six-speed manual is offered as an option. In Edmunds performance testing, an automatic-equipped Regal Turbo accelerated from zero to 60 mph in 8.4 seconds, which is well off the pace of both family sedans and entry-level luxury models. The EPA estimates 18/29/22 with the automatic and 20/32/24 with the manual.

The GS uses a version of this same turbocharged four-cylinder that's been upgraded to produce 270 hp and 295 lb-ft of torque. Here the six-speed manual transmission is standard, while the six-speed automatic is available as an option. The Regal GS's 0-60 time was a quick 6.2-second run with the automatic transmission. Curiously, the manual transmission model was slower at 6.9 seconds due to the difficulty of launching it smoothly. The EPA numbers with either transmission drop to 19/27/22.

The list of standard safety features for all 2013 Buick Regal models includes antilock disc brakes, traction and stability control, front seat side-impact airbags and full-length side curtain airbags. The standard OnStar system includes automatic crash notification, on-demand roadside assistance, an emergency button, stolen vehicle locator and active intervention, and remote door unlock. Rear-seat side airbags are standard on the Premium 2 trims and above.

In Edmunds brake testing, the Regal Turbo came to a stop from 60 mph in 122 feet, which is about average for cars in this class. The GS, with its bigger Brembo brakes and optional 20-inch summer tires, managed to stop in an impressive 107 feet.

In government crash tests, the Buick Regal received an overall rating of five stars (out of a possible five), as well as four stars for frontal impacts and five stars for side impacts. The Insurance Institute for Highway Safety awarded the Regal the highest score of "Good" in its frontal-offset, side-impact and roof strength tests.

On the road, the 2013 Buick Regal definitely feels sportier than the Buicks of old. The eAssist mild-hybrid powertrain is far from thrilling, but it's likely to work just fine for many buyers. The turbocharged engines are noticeably better, though there's often an unwelcome hesitation before the acceleration comes on strong. In an unexpected twist, we found the automatic transmission a better match for these motors than the unrefined manual gearbox.

The suspension delivers a smooth ride that's nicely complemented by the quiet cabin. Steering feels precise, though our editors found it a little too light on all but the GS model. Handling is above average, especially on the Turbo and GS models equipped with the Interactive Drive Control that offer three distinct settings for steering, suspension and throttle response. In the GS, the Sport mode is particularly impressive, though we think most buyers are likely to prefer the system's more relaxed Tour mode available only on the Turbo model.

Inside, the 2013 Buick Regal offers an attractively styled passenger cabin with an upscale look and feel, but we can't say it's really all that nicer than what you'll find in the latest midsize sedans from Ford, Honda and Nissan. Front seats offer good support in both spirited driving and more casual cruising. Rear seats aren't as comfortable, however, and the sloping roof line means both less headroom for tall passengers and reduced visibility out the back for some drivers.

The cockpit controls are dominated by too many similar-looking buttons, but the addition of the Intellilink touchscreen interface for 2013 is welcome. This consists of a large touchscreen with customizable menu icons. Intellilink also allows you to connect to services like Pandora or Stitcher radio via the Bluetooth system. The touchscreen interface has a clean layout and intuitive menu structure, but it proves problematic to use at times due to missed inputs and delayed reactions.

Out back, the battery pack for the eAssist powertrain cuts usable trunk space down to a mere 11.1 cubic feet. Turbo and GS models are better at 14.2 cubic feet, though the trunk's narrow width means bulky cargo like golf clubs are going to be a tight fit.