The front suspension has struts while the rear uses a torsion-beam axle to provide more interior space in the trunk. Again, major improvements were made last year, with new hydraulic suspension bushings in the rear and recalibrated solid bushings up front. Front and rear stabilizer bars on all models reduce lean in the corners. The Ion handles well on winding roads, tending toward understeer when driven very hard. The suspension feels a little squishy at high speeds, however. The ride is nicely damped on rough roads.

The ABS option comes with traction control and dynamic rear brake proportioning. The latter adjusts brake pressure according the load on the rear wheels. It sends more brake pressure rearward when the back seat and trunk are full. Under hard braking, it shifts brake pressure from the rear wheels to the front as the car's weight shifts forward, reducing rear-wheel lockup, for better, more stable braking.

The Ion's 2.2-liter four-cylinder engine develops 140 horsepower at 5800 rpm and 145 pound-feet of torque at 4400. This twin-cam engines gives the Ion good performance for the class. Sound deadening added for 2005 reduces filters out engine noise. Ions sold with this engine in California are certified as Super Low Emissions Vehicles (SULEV).

A new 2.4-liter twin-cam engine with variable valve timing has been added to the lineup for 2006. Like the 2.2, it's part of GM's Ecotec engine family, designed for low mass and compact dimensions. Twin balance shafts counteract engine vibration, and direct mounting of all accessories helps further reduce noise, vibration, and harshness. Optional on Ion 3 as part of the Enhanced Performance Package, the 2.4-liter develops 170 horsepower at 6200 rpm and 162 pound-feet of torque at 5000, numbers normally associated with midsize cars. The performance package includes stiffer shock valving and thicker anti-roll bars, front and rear.

A five-speed manual gearbox is standard with either engine. It works well, though the shifter is positioned slightly rearward from the ideal position.

The four-speed automatic, optional with either engine above, is a smooth-shifting unit that responds quickly to the throttle and doesn't hunt excessively between gears. Built by GM and designated Hydramatic 4T45-E, it represents a major improvement over automatics installed in 2003-04 Ions, which were built by outside suppliers. The GM transmission also allows the Ion to be flat-towed, which is why you so often see Saturns trailing behind large motor homes.

The supercharged Red Line Quad Coupe is a lot of fun to drive. It features a firmer suspension. The handling is sharper and more responsive, but you can feel and hear the bumps. The Red Line's sporty exhaust sounds good and the supercharged engine delivers good throttle response and quick acceleration performance. As with most powerful front-drive cars, there is some torque steer, but it's easy to control. The manual shifter feels tall, maybe a little ropey; but it's easy and fun to shift with easy clutch take-up. The pedals are arranged well, making it easy to heel-and-toe when braking and downshifting for corners, setting you up to accelerate out and charge down the next straight.

Summary

The Saturn Ion is a stylish compact with innovative features. It drives nicely and its base engine offers adequate performance. Ion delivers good value and lots of interior space for people and cargo. Saturn buyers report happier experiences when buying and servicing than with other brands. Dent-deflecting and rust-resistant plastic body panels add to the Ion's appeal.

NewCarTestDrive.com editor Mitch McCullough reported from Detroit and Los Angeles.

Model Line Overview

Model lineup:Ion 2 sedan ($11,925); Ion 3 sedan ($14,325); Ion 2 Quad Coupe ($12,925); Ion 3 Quad Coupe ($15,625); Ion Red Line coupe ($19,425)

Engines:140-hp 2.2-liter dohc 16-valve inline-4; 170-hp 2.4-liter dohc 16-valve inline-4; 205-hp 2.0-liter 16-valve supercharged inline-4

Transmissions:5-speed manual; 5-speed high-performance manual; 4-speed automatic

Safety equipment (standard):dual-stage frontal airbags; load limiting retractors with pretensioners for front seatbelts

Safety equipment (optional):ABS, traction control; side-curtain airbags

Basic warranty:3 years/36,000 miles

Assembled in:Spring Hill, Tennessee