Both of the 2007 Sonata's engines incorporate some of the latest developments in variable timing of intake valves, achieving the dual benefits of lower emissions and higher fuel efficiency. Both engines are rated LEVII ULEV (Ultra Low Emissions Vehicle) by the Environmental Protection Agency. Additionally, the V6 uses a variable-length intake manifold to fatten the torque curve and make more zip available over a broader range of engine speeds.

Fuel economy for the four-cylinder GLS with manual transmission, as estimated by the EPA, is 24 miles per gallon in the city and 34 mpg on the highway. The V6-powered SE and Limited are rated 20/30 mpg.

Acceleration is brisk in the four-cylinder and brings a grin to the face in the V6. Hyundai officials say the V6 will turn 0-60 miles per hour times of about 7.5 seconds, with a top speed of 130 mph. Shifts are executed easily with the five-speed manual, and chirping the front tires is even easier. The Shiftronic automatic transmission moves between gears smoothly, kicking down for passing with minimal hesitation. The automatic offered responsive performance while tackling the hills of San Francisco. In manual mode, the Shiftronic will upshift automatically when the engine bumps up against redline, and it declines to downshift at all, leaving that to the driver's preferences.

Steering is light and direct, with good on-center feel and directional stability. Brakes are mostly linear, and equipped with Electronic Brake-force Distribution, which improves stability and reduces stopping distances by balancing brake force between the front and rear tires; while ABS allows the driver to maintain steering control under hard braking. Yet we noticed little of the interference we've found with some more complex EBD-equipped systems, and then only in the final stages of a stop. The 17-inch wheel/tire combination makes its presence known on rough pavement, where the shorter sidewalls transmit more of the road's imperfections into the cabin. Wind and road noise is decently muted.

The suspension layout looks good on paper, with double wishbones in front, multiple control links in back, and twin-tube gas-pressure shocks and stabilizer bars all 'round. The V6 boasts a larger front bar to handle the larger engine's extra weight. But how it all works together still needs, well, work. Against the competition, which has been refining its suspension technology for much longer than Hyundai, the Sonata feels less polished, less of a whole. Not that there's anything wrong or necessarily lacking in the ride and handling. It's just that some of the transitions, in direction and between types and qualities of pavement, aren't as smooth as the look and feel of the Sonata promises. The front end tucks in nicely as steering is cranked in, but the car doesn't track as surely as expected. There's also the impression of poorly managed unsprung mass when the rear suspension crosses rough or broken pavement, which suggests the hard parts are a generation or two behind in the alloys used and how they're formed. Still, interstate-intensive travel, even at socially irresponsible speeds, is smooth and unruffled, which is no small achievement.