The Mazda6 midsize sedan entered its second generation for 2009 with an all-new exterior, and completely revamped interior, a new base four-cylinder engine and some new transmission choices.

Mazda introduced the original 6 as a 2003 model, replacing the popular 626 with a new single-digit designation and a whole host of improvements.

Now, though, the No. 4 Japanese automaker has taken this sporty sedan to a whole new level, making an already good car an even better competitor to the segment-leading Toyota Camry and Honda Accord.

This is an important segment, as more than two million U.S. consumers buy new midsize cars every year. There are at least 12 vehicles competing for those customers, with the newest generation of the Chevrolet Malibu now challenging the Camry and Accord's dominance of the segment, which also includes the sporty Nissan Altima.

With the original Mazda6, whose marketing efforts introduced Mazda's "zoom, zoom" advertising theme, Mazda created what it considered to be a combination of sports car and sedan, breaking from the somewhat boring practicality of the Accord and Camry.

The whole idea was to create a midsize family car that offered enthusiasts an affordable alternative to the run-of-the-mill sedans. The first Mazda 6 was a fun car to drive in all configurations, and quickly established itself as something different in a field of sameness.

The truth is in the driving, and our test car offered some of the most-spirited acceleration and confident handling that I've ever experienced in an (almost) affordable family sedan.

I say "almost" because our tester was the 272-horsepower, V-6 S Grand Touring model, the top-of-the-line version, whose price was $28,260 (plus $670 freight and options). That's nearly $10,000 more than the base Mazda6 with its four-cylinder engine, which begins at $18,550.

Still, even the four-cylinder model, with its 170 horsepower and standard six-speed manual transmission offers a fun driving experience - at a relatively bargain price.

Mazda said the new 6 takes everything the company "learned from the first-generation car, as well as lessons learned from volumes of customer feedback, and proves Mazda's commitment to continuous improvement."

It's also the first Mazda designed, engineered, developed, and manufactured "on U.S. soil with the intention of surpassing American customer needs in countless categories," the company said, adding that the goal was to instill "the soul of a sports car" into the new 6.

Key styling cues were taken from the Mazda RX-8 sports car, including the front fenders and the raked roofline. Interior design elements include round gauges, a three-spoke steering wheel, and a T-shaped instrument panel.

There is ample room for up to five adults, and the trunk has 16.6 cubic feet of space. The rear seat has a 60/40 fold-down feature to allow for longer cargo.

The base model is the SV, equipped with a 2.5-liter inline four-cylinder engine rated at 170 horsepower and 167 foot-pounds of torque. While the manual gearbox is standard, a five-speed automatic is optional.

The 3.7-liter V-6 Sport model, with 272 horsepower and 269 foot-pounds of torque, begins at $24,130. Only a six-speed automatic transmission is available with the V-6, but it has manual-shift capability for sportier driving.

Other trim levels include the four-cylinder Sport model ($20,250); the four-cylinder Touring model ($21,705); the four-cylinder Grand Touring model ($24,910); the V-6 Touring model ($25,075); and our tester, the V-6 Grand Touring.

The four-cylinder engine is a new Mazda design, and is available with either the base six-speed manual or optional five-speed automatic transmission. EPA fuel economy ratings are 21 mpg city / 30 highway with the five-speed automatic, and 20/29 with the manual.

The V-6 engine is the same one used in the Mazda CX-9 crossover utility vehicle, and it has EPA ratings of 17 city/25 highway.

Standard on all models are air conditioning, power windows/mirrors/door locks, four-wheel disc antilock brakes, electronic stability control with traction control, seat-mounted front side air bags, side-curtain air bags for front and rear passengers, an AM/FM/compact-disc stereo with six speakers, a tilt and telescopic steering wheel, two 12-volt power outlets, floor and cargo mats, and a tire-pressure monitoring system.

Sport models also get cruise control, an auxiliary audio jack, and remote keyless entry system.

With the four-cylinder Touring model comes 17-inch alloy wheels, an eight-way power driver's seat, advanced keyless entry system with pushbutton ignition, electroluminescent gauges, black decoration panel, leather-wrapped steering wheel and shift knob, center console sliding armrest, fog lights, trip computer and anti-theft security alarm.

The V-6 Touring models get the above extras, but the wheels are 18-inch alloys instead of the 17-inch.

Grand Touring models get heated leather seats, a memory for the driver's seat, a power passenger seat, rain-sensing wipers, dual-zone automatic climate control, auto-dimming rearview mirror with universal garage opening, automatic xenon headlights, heated auto-dimming exterior mirrors, LED rear combination lights, a blind-spot monitoring system, Bluetooth phone connection, and a ground illumination and interior lighting system.

The front bucket seats are slightly bolstered to allow for spirited driving without the driver sliding out of the seat. The rear seat offers adequate legroom and enough width for three people, but the middle position is more comfortable for a child than an adult.

Extras on our tester included a navigation system ($2,000); California smog certification ($100); and a power moon roof and Bose audio-system package ($1,750). With the Bose system came a six-disc CD changer and Sirius satellite radio.

All Mazda6 models are assembled at the joint Ford-Mazda plant in Flat Rock, Mich.

The automotive columns of G. Chambers Williams III have appeared regularly in the Star-Telegram since 1994. Contact him at 210-250-3236; chambers@star-telegram.com.

2009 Mazda6 sedan

The package: Midsize, four-door, five-passenger, four-cylinder or V-6-powered, front-wheel-drive sport sedan.

Highlights: Mazda's midsize sedan entered its second generation for 2009 with all-new exterior styling, a completely revised interior, and a new Mazda four-cylinder engine, among many improvements.

Negatives: Can get pricey for a mass-market midsize sedan.

Engines: 2.5-liter inline four cylinder or 3.7-liter V-6.

Transmissions: Six-speed manual or five-speed automatic (I-4); six-speed automatic (V-6).

Power/torque: 170 HP/167 foot-pounds (I-4); 272 HP/269 foot-pounds (V-6).

Length: 193.7 inches.

Curb weight: 3,258-3,547 pounds.

Brakes, front/rear: Disc/disc, antilock.

Trunk volume: 16.6 cubic feet.

Side air bags: Front seat-mounted, roof-mounted side-curtain for both rows, standard.

Electronic stability control: Standard.

Fuel capacity/type: 18.5 gallons/unleaded regular.

EPA fuel economy: 20 mpg city/29 highway (I-4 manual); 21/30 (I-4, automatic); 17/25 (V-6).

Major competitors: Volkswagen Passat, Honda Accord, Toyota Camry, Nissan Altima, Kia Optima, Hyundai Sonata, Chrysler Sebring, Dodge Avenger, Mitsubishi Galant, Chevrolet Malibu, Pontiac G6, Saturn Aura, Ford Fusion, Mercury Milan, Subaru Legacy.

Base price range: $18,550-$28,260 plus $670 freight.

Price as tested: $32,790, including freight and options (V-6 S Grand Touring model).

On the Road rating: 9.3 (of a possible 10).

Prices shown are manufacturer's suggested retail; actual selling price may vary.