When cars are midway through their life cycles, manufacturers often freshen the appearance a bit to keep up with the times.

For BMW's popular rear-wheel drive 5-Series sedan, the sheet metal changes for 2008 are minor, so if you liked the styling so far, you'll be just fine with the new one. It's under the hood where BMW has made major improvements.

This new model year, buyers still have three levels of the mid-size sedan to choose from. The base offering has had its numeric name changed from 525 to 528, but its engine remains the merely adequate 230-horsepower, inline six. The 550i remains on top of the lineup, with its 360-horsepower V-8 providing most of the fun of the bigger V-10-powered M5 model without the drawbacks of dismal economy.

Additionally, the 5-series has a six-cylinder sports sedan with power to match its superb handling.

The real change agent, though, is the new 535i, which is the focus of this profile. The new midrange offering adds twin turbochargers to the willing 3.0-liter inline six to make 300-horsepower, up dramatically from the 255 horses of last year's 530i.

This isn't the first appearance of BMW's turbocharged six. The engine made its debut last year in the up-level 3-Series cars and was an instant success. This new engine provides smooth, linear power and torque that rivals BMW's previous V-8. And the power gets to the rear wheels through a sport-shifting, six-speed automatic that offers plenty of driver control.

Acceleration is instant, making freeway assaults a breeze or leaving the apex of a challenging corner. The firm suspension feels just right for my posterior, with just enough damping to smooth the pavement's rough edges. And while the brake calipers aren't painted red, they clamp the vented rotors with plenty of authority.

The 5-Series eyebrows over the head and taillights are still curious to me, and the sedan looks a bit small for a mid-size offering. But its athletic appearance matches the performance potential and while there's just enough room in back for full-size adults, the trunk is a generous 14-cubic feet.

Few items were changed inside the 5-Series. The most obvious was the transmission control lever, a device that looks like it might function well as a manual shifter. But there's no manual offering for the 535, since the `Steptronic' does the work nicely. Most driving demands are accommodated in `Drive' mode. But slip the shifter left and `Sport' algorithms change the throttle response and shift sequence. In `Sport,' the shifter can be nudged fore and aft for manual paddling.

EPA fuel economy: City: 17, Highway: 26

Base MSRP: $49,400