The Good: The 2009 Volkswagen Jetta TDI is powered by a fantastic turbodiesel engine that combines great fuel economy with good torquey performance. The Bad: The interior is dull and joyless with a mediocre audio system. All or nothing packaging lumps all tech amenities into a single navigation option. The Bottom Line: The 2009 Jetta TDI's engine represents a great balance of driver-friendliness and eco-friendliness. We just wish the rest of the vehicle lived up to its prestige. Photo gallery:2009 Volkswagen Jetta TDIAfter winning the 2008 Green Car of the Year award, the 2009 Volkswagen Jetta TDI has become the poster child for Volkswagen's green efforts and one of the most difficult vehicles to keep on the showroom floor. But while most look at the TDI's fuel economy and see an eco-variant of the gasoline-powered Jetta, we chose to look at the torque numbers and see a performance variant. Don't believe us? Go ahead and Google "Jetta TDI Cup." It's quite possible that the Jetta TDI is the way for drivers to have their cake and eat it, by combining performance and eco-consciousness. Unfortunately, the Jetta TDI's jewel of a powerplant is encased in a shell of pure "meh." From the uninspiring exterior styling to the downright boring interior and low-level cabin tech, we can't help but wish for a bit more excitement from the total package. On the road To discern where the Jetta TDI ranks on the performance\/economy scale, we plotted a course up California's Pacific Coastal Highway (PCH) from CNET's San Francisco office to Fort Bragg. The Jetta TDI's gratuitous low-end torque seemed well suited for the PCH's low-speed switchbacks and dramatic elevation changes. To make things interesting, we aimed for an average fuel economy of 40 mpg for the 175-mile journey. After an uneventful journey through the streets of San Francisco, we found ourselves crossing the Golden Gate Bridge. We'd timed our journey to miss the lunch and rush-hour crowds, but with the Jetta's multifunctional display showing a meager 14.8 mpg, we knew that, even with clear highways, our work was cut out for us. The Jetta TDI surprised us with its solid performance and good fuel economy.Guiding the Jetta TDI up the PCH, we were pleased to see the average mpg steadily climbing. The TDI's 236 pound-feet of torque was making short work of elevation changes; its smooth swell of power pulled us through the snaking turns with surprising confidence. By looking ahead and focusing on maintaining momentum instead of gaining speed, we watched the mpg meter climb to 20 then 30 mpg. The Jetta TDI's steering and handling wasn't as sublime as that of, for example, the Honda Civic Si, but kept the vehicle planted and predictable through the hairpins and decreasing radius turns. Eventually, our fuel economy began to plateau at around 35 mpg. Each subsequent mile per gallon was a hard-fought battle, but we were still seeing meager gains. We finally reached our destination under the cover of darkness. The limited visibility greatly hampered our ability to smoothly maintain momentum. The fatigue of hours of concentrated driving and the appearance of wildlife at the road's side forced us to shift our focus to driving cautiously, rather than efficiently for the last leg of the trip. As we crossed the city limit into Fort Bragg, some 5 hours after the start of our journey, the Volkswagen's trip computer read 38.7 mpg averaged for the trip, short of our goal of 40 mpg, but still impressive considering the highly technical nature of our chosen route. At the end of the day, we were happy with the Jetta TDI's fuel economy.It bears mentioning that by the time we parked the car for the night, the average mpg for the day had risen to 40.2, thanks to a return journey over more conventional freeways. In the cabin The Volkswagen Jetta's cabin emphasizes substance over style, which is actually a nice way of saying "devoid of character." The Jetta's upright dashboard is an expanse of flat, black plastic. The seats are flat and unsupportive and wrapped in a black fabric Volkswagen calls V-Tex. The carpet is also black. The instrument cluster features black gauges on a black backdrop with plain white lettering. You see where we're going with this. The Jetta's interior looks like it was designed by someone who would never have to look at it, perhaps a robot, an algorithm, or a blind man. While everything functions as one would expect it, the Jetta's cabin just isn't a pleasant place to be. We'd like to see Volkswagen add some texture or--gasp--color to the gulag that is the Jetta's interior. In the center of the instrument cluster is the Multi-Function Indicator (MFI), a monochromatic, red backlit display displaying fuel economy, miles to empty, average speed, and audio playback information. Here users can also adjust a cadre of options for the various convenience features, such as the autolocking doors or daytime running lamps. The steering wheel features buttons for controlling the MFI and for adjusting audio volume. Interestingly, the telephone button is ever-present, even if Bluetooth hands-free isn't equipped. With nothing to connect to, the button merely mutes the stereo. The drab situation doesn't improve when it comes time to crank the tunes. Our Jetta TDI was equipped with Volkswagen's Premium VII six-disc, in-dash CD player. Audio sources include the aforementioned CD changer, which is MP3 compatible, available satellite radio, and an auxiliary input in the center console. With a total of 10 speakers at its disposal, the stereo does a fairly good job with stereo separation and staging. Unfortunately, this is one of those stereos that stages the audio behind your head, so all of the music sounds like its coming from the rear window. The audio system also seems to emphasize volume over fidelity, with boomy bass and mid ranges that muddy the higher frequencies. Users more interested in quantity of sound than quality will be the only ones who could possibly appreciate this. Anyone wanting a slightly more high-tech cabin experience can upgrade to Volkswagen's RN510 hard-drive-based navigation system, which features touch-screen GPS navigation with turn-by-turn instructions that are mirrored on the MFI in the instrument cluster, 30GB of hard-disk space for ripping audio, and a USB connection for digital-audio players. An iPod connection is available as a dealer-installed option, as is Bluetooth hands-free. Under the hood As plain vanilla as the Jetta TDI's cabin and exterior may be, this is a vehicle that's causing a lot of fuss in the automotive world. The reason lies under the hood: a 2.0-liter turbodiesel engine that produces 140 horsepower and a spectacular 236 pound-feet of torque while burning Ultra Low Sulfur Diesel fuel. Max torque is available as low as 1,750rpm. Here's what all the fuss is about: the 2.0-liter TDI engine.Although the diesel features 30 fewer horsepower than the inline-five of the gasoline variant, the abundance of low-end torque means the TDI gets off the line better. Sixty miles per hour comes in 8.2 seconds, matching that of the gasoline engine. The 2008 Green Car of the Year, the Jetta TDI is EPA rated for 30 city and 41 highway mpg. However, unlike a hybrid, the TDI engine won't automatically get good fuel economy for you, and requires thrifty driving to reach those numbers. In the hands of a lead-footed journalist, for example, we were able to hit the 41 mpg mark for individual highway trips, but only averaged 23 mpg for the duration of our testing over a mixed testing cycle. As noted in the "On the road" section, the TDI's chunky low end makes it suitable for low-speed technical courses that would leave a high-revving gasoline engine hunting for gears. Speaking of gears, our Jetta TDI was equipped with a six-speed, manual transmission. However, the Jetta's clutch pedal keeps us from being 100 percent enthused about the manual transmission. Featuring a deceptively long travel and short, but vaguely defined, engagement point, the Jetta TDI's clutch is, at times, difficult to modulate in stop-and-go traffic. Once the Jetta gets moving, the vague clutch becomes less of an issue and we were able to enjoy the fantastic shifter that just falls into its gates with smooth and reassuring clunk. But make no mistake, the Jetta TDI is no canyon carver. The transmission is geared a bit tall for optimal highway fuel economy. Additionally, the suspension and steering both pale in comparison to the competition from Honda and Mazda. In sum So, is the 2009 Volkswagen Jetta TDI the car that will save the world? Will it be the car that brings greenies and enthusiasts together? In short, it's close, but not quite there yet. While we like the Jetta TDI's fantastic turbodiesel engine's ability to combine eco-friendliness and good performance in a simple package without hybrid techno-trickery, we just don't think that the average John Q. Driver will spend much time at the top of the EPA's estimated fuel economy ratings. Then there's the small matter of the vehicle wrapped around the engine. The vehicle's aesthetic and cabin tech are, at best, uninspiring. Buyers are able to upgrade to the DSG automated-manual transmission for $1,100 and the RNS 510 hard-drive-based navigation for $1,990. As tested, our Laser Blue VW Jetta TDI weighs in at an MSRP of $23,270, including the $1,000 optional power sunroof. For that price, a greenie could have the Honda Civic Hybrid with its superior fuel economy, or a speed demon could pick up a Mazda Mazdaspeed3. However, the Jetta TDI represents a unique compromise between the two types of performance.