Redline is 6500 rpm, but the engine is happy zooming to 7000. The 16-valve head is quite sophisticated, with variable valve timing and a variable induction system that optimizes intake efficiency and torque. The block is aluminum, there's a cam chain rather than a belt, and the exhaust manifold is stainless steel. The engine is very smooth and quiet at consistent freeway speeds, and has a nice sporty sound when it's revving under acceleration. The 2.3-liter Mazda 3 with the manual transmission rates an EPA-estimated 26/32 miles per gallon City/Highway.

For 2006, Mazda has adapted variable valve timing and variable-length intake runners to the smaller, 2.0-liter engine as well. The spec sheet shows a why-bother gain of only 2 horsepower (from 148 to 150, both at 6500 rpm), and no change in rated torque (still 135 pound-feet at 4500 rpm), but those are only the peak number. The biggest benefit of both variable valve timing and a variable intake is usually a flatter torque curve while maintaining good peak horsepower. So while we haven't driven a 2006 Mazda 3i (or even seen a torque curve for one on paper), we suspect that that's the case here. And if so, it could mean a palpable gain in performance, across a broad rpm range, that is much larger than those 2 horsepower would suggest. EPA estimates for the smaller engine are 28/35 city/highway mpg with manual transmission, 26/34 with the automatic.

The standard five-speed manual transmission shifts beautifully, especially the upshifts, which were almost as smooth as an automatic, with no real driver effort. Mazda worked hard on designing the synchronizers and cable linkage for reduced friction.

Mazda now calls the optional automatic transmissions Sport A/T. (Last year it was Activematic.) Either way, it's a fancy name, but these are fancy transmissions. You can just put the lever in Drive and go, but they also feature a manual mode programmed for quick shifting. Left to shift on their own, they're smart, maintaining a gear going downhill for engine braking or uphill to reduce hunting. Sport A/T has four gear ratios when ordered on 3i, and five ratios with 3s.

Handling is quick and nimble, making the Mazda 3 fun to drive. It's a blast on winding country roads. It's also sharp, true and steady in emergency lane-change maneuvers. Mazda's Electro-Hydraulic Power-Assisted Steering (EHAPS) minimizes drag on the engine compared to a conventional belt-driven hydraulic system. Mazda claims it also reduces noise, vibration, and harshness. The Ford group in England designed the Mazda 3 suspension, but the final tuning was done by Mazda at its long, rolling test track in Hiroshima.

Mazda 3s models with the 2.3-liter engine come with slighter larger brakes than those on the 2.0-liter 3i. We found the brakes on the 3s to be quite effective and sensitive; a mere light touch on the brake pedal around town works nicely.