Can you really have fun driving a cushy family sedan? Of course you can, especially if you're able to shell out the $37,000-plus it takes to buy the really impressive Cadillac CTS midsize sport sedan with the up-level 3.6-liter V-6 engine and smooth-shifting Aisin six-speed manual gearbox.

Now, I realize that a manual transmission isn't for everyone, and might seem a bit out of place in a premium sedan such as the popular CTS. But for a driving experience that's more sports-car-like than you could imagine in an entry luxury sedan, our test car for the week would be a great choice.

Introduced four years ago as the replacement for Cadillac's slow-selling Catera sedan, the CTS was the first of the Caddies bearing the styling cues of the brand's new "art and science" design strategy.

The CTS came out of the box as a hit, and it's still on a roll. The car is aimed at consumers age 35-50, and it is among this age group that the car is doing well, dealers and Cadillac officials report.

It's also the most highly regarded sedan in its class among buyers after the first three months of ownership. It won the 2006 Vehicle Satisfaction Award for entry luxury cars from the automotive marketing firm AutoPacific. The CTS beat the Lexus ES 330 for the top spot.

Cadillac says sales of the CTS have increased significantly each year since its introduction four years ago. The GM division reported sales of 61,000 of the CTS in 2005, compared with about 38,000 in 2002, the year it was introduced.

Intended for baby boomers and up-and-coming Generation Xers who had never considered buying a Cadillac, the CTS was billed from the start as a sport sedan for the enthusiast driver. And while the first CTS hit the mark on styling, the promised sporty performance was a bit lacking. Its 3.6-liter V-6 engine cranked out 220 horsepower, which was more than adequate for everyday driving, but not for the CTS to be regarded as an enthusiast's car.

So for 2004, Cadillac rolled out a new version of the V-6 with variable valve timing and a big boost in power: 255 horsepower and 252 foot-pounds of torque.

And even though Cadillac had been offering a five-speed manual gearbox in the CTS from the start, a new six-speed manual was introduced last year as a perfect companion to the 255-horsepower engine.

While it still isn't the most-powerful six-cylinder sport sedan in its class (the Acura TL and Infiniti G35 both have 270 horsepower, for instance) the CTS with the 3.6-liter engine and six-speed manual somehow seems sportier.

With the CTS and G35, you get rear-wheel drive as the standard arrangement, while the TL still comes with front drive, not considered the optimum setup for a true sport sedan. Other competitors offer similar power -- such as the 255-horsepower Audi A6 with a 3.1-liter V-6 and the BMW 3-series, whose midlevel engine is a 255-horsepower inline six. The BMW also is offered with a six-speed manual, and rear drive is standard. The Audi comes with front drive, but all-wheel drive is available.

The styling of the CTS is a bit more inspiring than that of the TL and most other competitors except the G35. The sculpted hood, aggressive grille and chiseled exterior of the CTS make it stand out among the current crop of sporty, premium sedans on the market.

Even before the more-powerful engine appeared, the styling of the CTS was a big draw, bringing a lot of new owners into the Cadillac fold.

Inside, placement of gauges and controls seems to be well thought-out, and the front sport bucket seats are quite comfortable, holding their occupants in place even in hard turns. The back seat can hold up to three adults rather comfortably. The trunk is a bit tight for this class, at 12.8 cubic feet, but the rear seat can be folded to increase cargo space.

With the 255-horsepower engine and the manual gearbox, the CTS can go from zero to 60 mph in just over six seconds (6.7 seconds with the five-speed automatic transmission). The engine is all-aluminum, has dual overhead cams with four valves per cylinder, and it has fully variable valve timing and a dual-stage variable intake manifold. Cadillac also uses this engine in the CTS-based SRX sport wagon.

How about fuel economy? Not a problem. The EPA ratings are 17 miles per gallon in the city and 26 mpg on the highway, but with our test car we averaged just over 20 for the week -- which included mostly around-town freeway driving. I have no doubt that careful driving could achieve the 26-mpg mark on a long highway cruise.

To support the more-powerful engine, Cadillac made some other changes to the CTS, including a performance-tuned suspension that included new shock absorbers.

Of course, there is an even sportier model on the market. Cadillac last year introduced the CTS-V, with a Corvette V-8 engine that pounds out 400 horsepower and 395 foot-pounds of torque. That car is considerably more expensive, though, as one might expect. It starts at $51,395 (including freight).

And for those who might not need even as much power as the 3.6-liter model, there is an entry level CTS with a 210-horsepower, 2.8-liter V-6 engine that starts just under $30,000.

Cadillac has even extended the CTS into the racing world. A race version of the CTS-V won the 2005 Driver and Manufacturer's titles in the SPEED World Challenge GT class.

For 2006, the 3.6-liter CTS Sport model we tested (base price $36,770 plus $720 freight) comes with a sport-performance package that includes new performance brakes; revised suspension tuning; Xenon high-intensity headlights; StabiliTrak stability control system; tire pressure monitoring; and a limited-slip differential.

Included also was the 18-inch Sport Appearance Package, which brought 12-spoke, 18-inch polished wheels; restyled rocker moldings; dual chrome exhaust tips; a new mesh-style sport grille; and a rear spoiler.

Cadillac says that its "Driver Shift Control" is standard on all 2006 CTS models with automatic transmission. However, our car came with the six-speed manual gearbox.

Other standard equipment on our car included leather seats and leather-wrapped steering wheel; interior wood trim; dual-zone automatic climate control; power driver's seat; cruise control; auto-dimming rearview mirror; power windows/mirrors/door locks with remote; driver-information center; front seat-mounted side air bags and head-curtain air bags for front and rear passengers; fog lights; automatic headlights; and, of course, GM's OnStar system with a year of basic service.

The only extra on our vehicle was a Bose audio system upgrade ($1,000) with a six-disc, in-dash CD changer. XM satellite radio is standard.

Total sticker on our car was $38,490, including freight and the Bose system.

2006 Cadillac CTS sedan
The package: Premium, midsize, four-door, five-passenger, rear-drive, V-6 or V-8 powered sedan.
Highlights: Using Cadillac's new "art and science" design theme, this is a strikingly beautiful, great-performing entry luxury sedan.
Negatives: Knee room can be tight for rear passengers.
Engine: 2.8-liter V-6; 3.6-liter V-6; 6.0-liter V-8.
Transmission: Five-speed automatic or Aisin six-speed manual.
Power/torque: 210HP/194 foot-pounds; 255HP/252 foot-pounds; 400HP/395 foot-pounds.
Length: 190.1 inches.
Curb weight: 3,568-3,850 pounds.
Brakes, front/rear: Disc/disc, antilock standard.
Trunk volume: 12.8 cubic feet.
Fuel capacity/type: 17.5 gallons/unleaded regular.
EPA fuel economy: 16-18 miles per gallon city/25-27 mpg highway.
Major competitors: BMW 330i, Lexus ES 350/IS 300/GS 300; Mercedes-Benz C320; Audi A6, Acura TL, Saab 9-5, Infiniti G35.
Base price range: $29,270-$50,675, plus $720 freight.
Price as tested: $38,490 (3.6-liter Sport model with freight and options)
On the Road rating: ***** (five stars out of five).

Prices quoted are manufacturer's suggested retail; actual selling prices may vary according to manufacturer and/or dealer rebates, discounts and incentives, if any.

G. Chambers Williams III is staff automotive columnist for the San Antonio Express-News and former transportation writer for the Star-Telegram. His automotive columns have appeared regularly in the Star-Telegram since 1995. Contact him at 210-250-3236;