2008 Mercedes-Benz C-Class

Glancing at the squiggly blue line emerging on the slick, seven-inch navigation screen, a smile crosses our face. Yep, now we're going to have some fun.

We've been rolling along a mountain highway south of Valencia, Spain, in our black C350 Avantgarde (that'll be Sport in the U.S.) test chariot, and as expected, the new C-Class is eating up the miles like a champ. As it's Mercedes's worldwide best-seller, the company has put a massive amount of work into sharpening up its fourth-generation model, and it shows. It had better.

The new car breezes along on the freeway as you'd expect a well-engineered German sedan to do, its 3.5-liter V-6 (making 268 horsepower and 258 pound-feet of torque) and Mercedes's now-ubiquitous 7G-Tronic seven-speed automatic working in harmony at 70-plus mph.

The slightly bigger cabin is quiet and comfortable. Multiple changes for the better inside include standard eight-way-adjustable seats, improved gauge work, and a Comand interface that folds neatly into the top of the dash when not in use, controlled by Benz's spinning knob on the center tunnel. Improved safety is always a big concern for the Daimler boys. Seven airbags come standard, and the optional Pre-Safe occupant-protection system is among the many new safety features available.

As the nav directs us off the main highway and toward the bends, it's time to make our final preparations. Hit sport button. Check. Change transmission to sport mode and locate paddle shifters atop new three-spoke steering wheel. Check. Apply sunglasses and look cool. Check.

The sport button activates what Mercedes calls Advanced Agility (an enhancement to the sport's standard Agility Control package), a system designed to firm up the 350 Sport's self-adjusting suspension dampers and optimize throttle response. In addition, a quicker steering ratio and speed-sensitive steering help improve the wheel feel. With the seven-speed in sport mode, more aggressive shifting also is available at our thumbtips.

Working the paddle shifters, we push the C-Class through sweeping lefts and rights in search of body roll. We're not finding much, thanks in part to sport shocks and springs and a beefed-up anti-roll bar added to essentially the same front-strut/five-link-rear layout that underpins the outgoing model. A switch to aluminum suspension links is new, and ride height has been lowered by a half inch. The adaptive brake system, adopted from the S-Class, takes many a stomping in stride. The sweet, AMG-sourced 18-inch rims on our tester, shod with 225/40ZR18s out front and 255/35ZR18s at the rear, never squeal for mercy.