The Good: The 2009 BMW 335d's diesel engine delivers excellent fuel economy, with little performance compromise. The new iDrive controller works very well, and hard-drive-based navigation provides very detailed maps. iPod integration and Bluetooth phone support prove capable and easy to use. The Bad: BMW puts too much control on initial acceleration. Options run up the price of the car quickly. The Bottom Line: The 2009 BMW 335d is an economical performance car with room for four people and cabin electronics that measure up with the latest and greatest. Photo gallery:2009 BMW 335dWe know that modern diesel cars no longer spew foul-smelling black smoke from the tailpipe, that the engines don't rattle so much you'll think the sun visors are going to fall off, and that they can accelerate quicker than the time it takes the light to turn back to red. But can a diesel be a performance car? BMW answers the question with the 2009 335d, a new choice for the U.S. market that combines the brand's engineering prowess in making sports-luxury cars with new technology that makes the car meet the most stringent emissions requirements. In fact, the 335d looks the same as a gasoline-powered 335i, and even has the same displacement engine, a 3-liter inline six cylinder with twin-turbochargers. But the power specifications make the driving character insanely different. On the road The 2009 BMW 335d delivered to our garage came plastered with an Efficient Dynamics and BMW Advanced Diesel wrap on the sides, just as we've seen on auto show floors for the past couple of years. Fortunately, you can get it without the wrap, in one of 12 colors. The new iDrive main menu lists the various car functions (a much more practical interface than the former quadrant system). We were ecstatic to find the car equipped with the new generation of iDrive, which does away with the quad-menu in favor of the much more practical list menu. Better yet, the new system uses a hard-drive-based navigation system with live traffic and detailed maps. We spent a half hour just scrolling the map around to see 3D models of major buildings in San Francisco. Transamerica Pyramid? Check. SF MOMA? Check. Exploratorium? Check. AT&T Ballpark? Check. We paired an iPhone up with the Bluetooth system, and it made our Contacts database accessible on the car's LCD. Then we plugged the same iPhone into the iPod port, and could play our music through the car's stereo. Our cabin tech set up, we headed out for the open road, immediately noting that the 335d felt no different from any other BMW. The wheel had the right amount of resistance as we crept through city streets and the throttle gave plenty of room to modulate power to the wheels through the car's six-speed automatic. Although there is slightly more engine noise outside the car than a gas version, inside the 335d sound is nicely deadened. The navigation system features detailed renderings of major buildings.As we got the car onto faster roads, we noted the low rpms on the tachometer--the engine speed hung between 1,000 and 2,000 revs, with redline at only 5,000. But the 335d had no problem keeping up with and passing other cars, and ably climbed hills at speed, showing no strain. Into the twisties, with the automatic in its sport program, the high torque of the diesel engine made itself known. A turn was coming up; we hit the brakes, and then powered through, and that unbelievable torque started to make bad things happen. Traction control lights came on, the car shimmied back and forth, and we wrestled it back into a straight line. OK, with less power in the turns, the car behaved better, but the torque was still making the traction control lights flash on the dashboard. We started to suspect the 335d was equipped with extra slippery tires, but no, just the same stock Bridgestone Turanzas as on other BMW 3-series cars. The truth is, you just can't drive the 335d like you would a gasoline-engine car. During some fast-start testing, we determined that BMW probably retuned traction control and the automatic transmission to keep that huge torque from constantly lighting up the tires, as we could only pull off a too-controlled launch. When we tested the 335d, diesel fuel cost 35 cents more than premium gasoline per gallon. On a very positive note, an entire day spent in a mixture of high-speed freeway driving, ripping around country roads, and idling in a bit of slow traffic left the tank down by only half, and the trip meter showing an average fuel use of 30.9 mpg, on the high side of the EPA range of 23 mpg city and 36 mpg highway. In the cabin After years of iDrive hatred, BMW finally modified the system to make it much more usable. The hardware is essentially the same, with a joystick\/knob\/button as the main controller, but BMW added some buttons for quick access to major functions such as navigation and audio. We've always contended that the real fault in iDrive lies in the software interface, and this part has been completely redone by BMW. The main menu, which had four function areas you would select with the joystick, has been swapped for a simple list, where you select a menu item by pushing down on the knob. With the former system, BMW was limited in how many new applications it could introduce without burying everything under submenus. With a list, as many items as needed can be added. The new iDrive hardware isn't radically different from previous versions, but now includes quick access buttons for navigation, phone, and audio.Along with this interface adjustment comes the new navigation system. Its feature-set is largely the same as the previous one, offering live traffic information overlaid on the maps, with very good automatic detours around slow traffic. But the performance is better, with faster map refresh and the capability to easily browse the map. And as we mentioned before, the map detail has been improved greatly, with nicely rendered buildings to use as landmarks, and even topographical features on the 3D perspective map. But BMW hasn't started adding other information sources, such as gas prices or weather, like we've seen with Ford and Acura. And the navigation system doesn't do text-to-speech, so it won't read out street names to you. We are very pleased with the audio sources available in the 335d, which include iPod integration, a USB port, satellite radio, and onboard music storage. With the latter, put a CD in the player, and you can choose to rip it to the car's hard drive. There is only a single disc player, but you hardly need a disc changer with all these options. HD radio is available, but wasn't installed in our car. The interface for iPod integration makes finding music easy, even if you have a 160GB iPod.Lacking the premium audio option, we were stuck with a simple six-speaker setup that didn't do much for music. The sound was reasonably strong, suggesting good amp power, but it lacked clarity. There is a 13-speaker Logic7 audio system available that would have improved matters, but still would have fallen short of the best audio systems we've heard. Bluetooth integration remains a high point of this cabin tech package. The new iDrive interface makes it easier to access. After pairing a phone, the system makes the phone's contact list available onscreen almost immediately. Although we didn't have it on this car, BMW also makes an adaptive cruise system available on the 335d, letting the car automatically match speeds with cars ahead. Under the hood The 2009 BMW 335d uses a common-rail diesel-injection system on a 3-liter, inline, six-cylinder engine, getting forced air from twin turbochargers. BMW designed this turbocharger system with the intention of negating turbo lag by using one fast-and-small turbocharger that cranks up during initial acceleration, and a second, larger turbo that picks up as engine speed rises. This twin-turbo engine puts out 425 pound-feet of torque, which gets the 335d accelerating like a freight train, once it is underway.Turbo lag is not apparent in the 335d, although that may also be due to the way it regulates initial acceleration. The engine puts out only 265 horsepower, but manages a whopping 425 pound-feet of torque, and it seems BMW put some electronic regulation to keep the rear tires from spinning out of control. We did some testing by first hitting the DTC button once, which limits traction control, then holding the button down, which turns off the road-holding electronics. With either setting, stomping the accelerator from a stop leads to the car rolling slowly forward, initially, with no tire-burning theatrics. But the power quickly picks up, leading to a satisfying freight train feeling as the 335d heads toward the triple digits. Our car lacked the Sport package, which would have included a sport-tuned suspension, resulting in some mundane performance in the turns. The car stays nicely balanced in the corners, but just doesn't have the same tight feeling you get from the 3-series when it has the Sport package. The absence of the Sport package also means the car lacks paddle shifters for the six-speed automatic's manual mode, but we're fine with that, as we never liked BMW's paddle shifters. The transmission still has a sport mode, which does an excellent job of downshifting in anticipation of cornering. Emissions ratings aren't published yet for the BMW 335d. In sum The base price of a 2009 BMW 335d is $43,900. Our vehicle was equipped with the $1,150 Cold Weather package and the $2,650 Premium package, which doesn't add much besides autodimming mirrors and the BMW Assist service. The smart key is an extra $500 and the park distance control system is $700, but the most important features, from our Car Tech view, are the $400 iPod and USB adapter and the $2,100 navigation system. A couple more options in our car brought the total to $52,820, with destination charge. With the 335d's low fuel consumption and high performance, we gave it an outstanding rating for power-train tech. For cabin tech, it earns an excellent rating. The navigation, Bluetooth phone support, and audio sources don't disappoint. And it also features an excellent design, mostly in the new iDrive interface. The exterior is good, but a little bland.