Anyone who has planted themselves behind a BMW inline six-cylinder engine knows just how smooth and refined they are, but that didn’t stop the company from adding brand-new, redesigned engines that boast more power and better fuel economy than before.

Each 2006 BMW 3 Series is equipped with a new 3.0-liter, dual overhead cam, inline six-cylinder engine featuring Double VANOS variable valve timing and Valvetronic electronic throttle technology to develop maximum power, optimum efficiency, and meet tough Ultra Low Emission Vehicle-2 (ULEV-2) standards.

The engine installed in the 325i sedan generates 215 horsepower at 6,250 rpm, 31 more than last year. Torque peaks at a low 2,750 rpm, where 185 lb.-ft. of twist is available. More power combined with a lower torque curve brings the 2006 325i’s zero-to-60 acceleration time down to 6.7 seconds with the manual transmission and 7.2 seconds with the automatic, according to BMW.

The engine installed in the 330i might be exactly the same size, but it’s got three-stage induction (rather than single-stage in the 325i) and revised software mapping to generate 255 horsepower at 6,600 rpm and 220 lb.-ft. of torque at 2,750 rpm. BMW says that the 2006 330i will run to 60 mph in 6.1 seconds with the manual transmission and 6.3 seconds with the automatic.

In both models, a six-speed manual transmission drives the rear wheels, with a new six-speed Steptronic automatic available as an option. Steptronic includes normal, sport, and manual modes to suit the whims of the driver. Starting in the fall, a Sequential Manual Gearbox (SMG – a true manual transmission that does not have a clutch and that can operate in automatic mode if desired) will be offered on the 330i equipped with the Sport package.

Regardless of package purchase, the suspension is completely redesigned, and BMW hasn’t strayed far from the successful formula of front MacPherson struts and a rear multilink setup for the 2006 3 Series. Up front, the new double-pivot strut suspension is composed entirely of aluminum, and the five-link setup in back is brand new. Standard and Sport suspension calibration is offered, and the fast-reacting Active Steering system from the 5 Series is available on cars equipped with the Sport package. Thanks to the use of lightweight materials in the front suspension and engine blocks, BMW has been able to maintain close to an ideal 50/50 front-to-rear weight distribution for optimum handling and responsiveness.

Run-flat tires are standard on both the 325i and the 330i, and they’ll go 150 miles at 50 mph before requiring replacement, helping to keep owners from becoming stranded someplace unsafe. Standard equipment for the 325i is a 16-inch aluminum wheel wearing 205/55 all-season tires, and for the 330i it’s 17-inch alloys shod with 225/45 all-season rubber. A tire pressure monitoring system is also standard. Add the optional Sport package to either model for plus-one wheel sizes and lower-profile performance tires.

Vented four-wheel-disc brakes with ABS and electronic brake proportioning are standard, equipped with several features to boost performance for 2006. Brake standby prepares for a panic stop when the driver’s foot is abruptly released from the accelerator, under the assumption that rapid braking is going to be required. Fading compensation reacts to rising brake temperatures, and accordingly adjusts hydraulic pressure relative to pedal force. Brake drying removes wetness from the brake rotors in the rain, based on sensor readings from the standard rain-sensing wiper system. Soft-stop automatically helps generate smoother stops, and start-off assistant holds a 3 Series with a manual transmission in place on a hill until the clutch is released and the accelerator is depressed.

There’s also a standard stability and traction control system called Dynamic Stability Control (DSC). DSC operates in three modes, adjusted using the button mounted in the center of the dashboard. In normal mode, DSC uses the braking system to halt skids early, bringing the 3 Series into line as quickly as possible. Depress the DSC button once to expand the safety net, allowing you to have a good time by drifting and sliding and peeling the rubber a little bit before DSC steps in to quell the fun. Depress the DSC button and hold for three seconds, and the system completely disengages, leaving you to your own devices should you hit an unanticipated wet, snowy, or sandy spot mid-turn.