In our fast-paced world as international men of mystery, the arrival of our VW Jetta TDI was ever-so-slightly underwhelming. The two-liter 140hp engine had plenty of torque and it would return excellent fuel economy, but it wasn't exactly sexy...
Like your grandma coming to stay, you pretend to be happy about it, but secretly dread hours of scrabble at the kitchen table. But we have to admit the old girl surprised us.
Like a comfortable pair of shoes, the TDI quickly became the weapon of choice for long journeys. Sure, there were faster, more dramatic ways to arrive, but moving around Los Angeles involves hours of mind-numbing traffic. The TDI was always comfortable, dependable and rewarded you with great mpg figures.
Before we knew it, the Jetta had 20k on the clock in 12 months and we wanted it to stay. What's more, every journey became another chance to set a new economy record.
Of course, we did our best to give it some sex appeal - I'll avoid the temptation to complete my grandmother metaphor here for obvious reasons... The first thing we did was address the chassis, which was best described as "sloppy".
Chassis Driving a diesel requires a different mindset, something Justin and I grasped but Sam failed to comprehend. It's not about powering away from the lights (although the low rpm torque usually meant you were first away), it's about preservation of momentum and short-shifting to ride the torque (which is why you need a manual trans...).
With its tepid acceleration, once the TDI is up to speed, you do everything to keep it there. You certainly don't want to slow for corners, since you'll just have to accelerate all over again. So we needed to uprate the suspension, brakes and tires ASAP.
Sam and I split the duties. He got the bouncy bits and I did the rest. And so we had KW Variant 3 coilovers fitted, complete with adjustable bump and rebound.
I have to admit, this was overkill. We weren't going to track the TDI, and yet the KWs were surprisingly supple given their single-minded purpose. Of course, we never adjusted the settings once Justin had got it sitting and riding as we wanted, but it's nice to know you can...
For my part, I felt duty-bound to fit 19" BBS wheels. I don't think I need to explain why - just look at them!
We got a set of 19x8" BBS CH and bolted them to the car. They looked perfect from the second they arrived and I won't hear anything to the contrary.
Rubber was another simple choice for the TDI. We insisted a set of 235/35 R19 Contintental ContiSportContact 3 tires were fitted all round, and we never had to think about them again.
Admittedly, we were tempted to go with R-compound tires, reasoning that the V3 suspension and our desire for maximum grip would be best served by radical rubber. However, I knew we'd be using the TDI in all weather, on all occasions, so we needed something as tenacious and dependable as the car itself; hence the Contis.
As for the brakes, the TDI pedal was rather spongy. And although the car stopped well eventually, it didn't inspire confidence for our late-braking maneuvers. A set of big brakes couldn't be justified with 140hp, so we decided to upgrade to drilled EBC rotors and Green Stuff pads. These provided greater reassurance and so the chassis transformation was complete.
Exterior One of our favorite mods for the Mk5 Jetta was VW's "Thunder Bunny" body kit designed by Derek Jenkins' design crew when he worked on VW's SEMA concept cars. It was so popular, VW put it into production and later used it on the Jetta TDI Cup racers.
The deep VW Votex front spoiler, side skirts, rear apron and trunk lip spoiler are manufactured to OE standards from flexible plastics that look insanely stylish. I can't tell you how many times we've been stopped and complemented on the car, or asked what it is...
Considering our original reservations about the Mk5 Jetta's overall styling, we feel Project TDI is both handsome and intrinsically Euro.
Torque As many of you are aware, the problem with tuning a brand-new model is the availability of parts. And while the TDI models have been available in Europe for decades, the US cars had subtle differences.
Fortunately, we were able to find a 2.5" stainless steel cat-back system with Borla muffler from Techtonics Tuning and cold-air intake from Euro Sport Accessories.
Both leave the sophisticated emissions equipment intact, but it was inevitable that this was where most of the engine's restrictions would lie. As we previously reported, we didn't see improvements on the dyno with either part. But we were hoping to uncork the car with software.
Again, the correct program took a while to perfect and we tried a few development downloads from Revo Technik until finally hitting the right code.
It took a few minutes to upload the program into the Jetta's ECU from the laptop before we could return to the dyno. In stock form, the TDI had put down 126.3hp at 3446rpm and 226 lb-ft at 2316rpm. The new software simply built on VW's good work. The power and torque curves mirrored the stock curves but with a 15-20% increase throughout the power band. As you can see from the graph, the torque rises early at a loping 2200rpm, delivering a peak of 274 lb-ft at 2373rpm, while power peaks at 3672rpm, producing 146.4hp at the wheels.
Our TDI holds the extra grunt until the end, resulting in a car that pulls so effortlessly from low rpm we find ourselves rocketing away from the lights without even trying. By shifting early and riding that delicious torque curve you can get the Jetta to illegal speeds in the blink of an eye.
The Revo software has transformed the car to the same extent as our chassis mods. We now have a machine that looks, handles and performs to our liking. And it will still return anywhere from 40-50mpg on a freeway run, depending on the driver...
Of course, you could skip most of these steps and buy the fully warrantied Jetta TDI Cup Edition that's coming to VW dealers. It's basically a Jetta TDI built to GLI spec with the Thunder Bunny body kit. And although power is stock, it does get bigger brakes and GLI sway bars (so a call to Revo would be in order).
We'd like to thank our friends at DC Performance in Los Angeles, Canyon Racer in Mission Viejo and Euro Sport Accessories in Anaheim for the repeated use of their dyno facilities during the project's development.
Engine: 2.0 liter four-cylinder turbo-diesel with Revo Technik software, Techtonics Tuning 2.5" stainless steel cat-back exhaust, Euro Sport Accessories intake
Drivetrain: stock six-speed manual
Brakes: EBC drilled/slotted rotors and Green Stuff pads
Suspension: KW Variant 3 coilovers
Wheels & Tires: 19x8" BBS CH wheels, 225/35 R19 Continental ContiSportContact3 tires
Exterior: VW Votex front spoiler, side skirts, rear apron, trunk spoiler
Contact: BBS Wheels (bbs-usa.com), Continental Tires (conti-online.com), KW Suspension (kw-suspension.com), Revo Technik (revotechnik.com), Techtonics Tuning (techtonicstuning.com), DC Performance (dcperformance.com), VW (vw.com), Canyon Racer Motorsports (canyonracermotorsports.com)
If there was a complaint I had with our TDI, it was power. Don't get me wrong, it had decent torque at low rpm, but it wasn't enough to pass a soccer mom in a Nissan Murano. This didn't bother me much, because I was returning an average of 40mpg on most journeys. It was both serene and light on the pocketbook. But the car lacked the authority on the road of faster project cars like our 135i or Silverstone GTI.
But then everything changed. After its Revo re-flash, the new programming has breathed new life into our TDI. The extra torque and horsepower is easily noticeable. Past 2000rpm, the Jetta pulls hard. But most importantly, it holds the power for longer.
With the stock programming, power would die early, making me want to shift sooner. Yet the Revo software has made it feel stronger until near redline. The spool of the turbo is also more prominently voiced since the boost was increased. -Sam