2010 Volkswagen Jetta TDI
2010 Volkswagen Jetta TDI. Click image to enlarge

Related articles on Autos
Long-term test: 2010 Jetta TDI, Part one
Jetta named most-efficient wagon
Inside Story: 2009 VW Jetta TDI
Jetta TDI named Green Car of the Year
Test Drive: 2009 VW Jetta TDI

Manufacturer’s web site
Volkswagen Canada

Join Autos’s Facebook group
Follow Autos on Twitter

Review and photos by Chris Chase

Find this vehicle in Autos’s Classified Ads

Photo Gallery:
2010 Volkswagen Jetta

One of a diesel car’s raisons d’etre is to save fuel, but initially, our long term Jetta TDI didn’t seem to be living up to that expectation. Average fuel consumption in my mostly city driving routine was as high as 9.0 L/100 km at one point, shortly after I picked the car up with a usable fuel range of about 600 km per tank of diesel. Based on the car’s 6.7 L/100 km official fuel consumption rating and its 55-litre tank, the car should be capable, ideally, of going a little further than 800 km on a tank in city driving.

But as it turns out, there were a couple of things at play that affected my car’s performance early on. First, the car itself was brand new when I got it, with just 175 km on the odometer, and temperatures were very cold, with frequent night-time lows of minus 15 to 20 degrees Celsius, and daytime highs that struggled to make it above minus 10.

2010 Volkswagen Jetta TDI
2010 Volkswagen Jetta TDI. Click image to enlarge

Then came mid-January, which brought a mini-thaw, with temps hovering around the freezing mark. By that time, the Jetta had accumulated 1,600 km and its engine was “broken in,” and voila – fuel consumption has dropped noticeably (my average is just over 8.0 L/100 km as I write this, though this number is cumulative, since the beginning of the test).

One of the negatives of driving a diesel in the winter came early in the test, when the weather was cold: diesels take a long, long time to get up to operating temperature and provide enough heat to warm the cabin. Also, an idling diesel simply won’t get warm in sub-zero temperatures, so starting and driving away gently is the best way to get heat as soon as possible. If you get stuck in bumper-to-bumper traffic in your TDI, well, you`re gonna be chilly until you can get up to speed again.

2010 Volkswagen Jetta TDI
2010 Volkswagen Jetta TDI
2010 Volkswagen Jetta TDI. Click image to enlarge

I’m grateful for my tester’s block heater, then, which cuts warm-up time dramatically; the same plug – conveniently located in the front bumper – also powers a battery warmer, for easier starting in the cold. I’m even more thankful for the heated seats that come standard in the Jetta’s Highline trim that my tester wears. (With the TDI engine, heated front seats are available in the base Trendline trim, and standard in higher trims.)

The Jetta’s TDI engine uses tried-and-true glow plugs – small heating elements in the combustion chambers – to ease cold weather starting. The recommended starting procedure here differs a little from that of a gasoline-powered car: turn the key to the “run” position, wait for the glow-plug indicator light to go out, and start the car. If the car has been plugged in, the light stays on for about two seconds, and if the car was left unplugged, it will glow for six or seven seconds. You can ignore the light and start the car right away, but it will simply crank until the glow plugs have done their job. Regardless, the car has been flawless in starting, no matter the conditions.

This car’s long warm-up times serve to highlight one of the fundamental differences between diesel and gasoline engines. According to the FAQ section at TDIClub.com, diesels are more fuel efficient because a higher percentage of the fuel’s energy is converted into power, rather than heat. Given that, I’d suggest that heated seats are almost a necessity in a winter-driven TDI car.

Another potential downside to choosing a diesel relates to a local dealer`s recommendation to add diesel conditioner to the Jetta`s tank at every fill during cold weather. This additive prevents diesel from `gelling` in chilly temps. Nowadays, most diesel available is pre-treated to prevent gelling, but if you`re unsure of the source of the fuel you`re using, the roughly $8 investment for a bottle of conditioner, which is enough for several tankfuls, is a minor expense. Less convenient is what to do with the bottle once the seal has been broken. The obvious place to keep the bottle is in the trunk, where it`s easily accessible when you fill the car, but, naturally, the bottle leaks after the original seal is broken, and I learned how difficult the smell of this stuff can be to get out of the trunk carpeting when even a little of it spills. Now, the conditioner lives in the basement until I need it.

2010 Volkswagen Jetta TDI
2010 Volkswagen Jetta TDI
2010 Volkswagen Jetta TDI. Click image to enlarge

Diesels are all about torque, and while the Jetta TDI`s 140 horsepower is at the low end of what most compact sedans are available with now, the engine`s 236 lb-ft of torque helps make up for it. Still, if you’re like me and don`t have much experience with diesel engines, the motor`s power characteristics are different from those of a gas engine. Most of the engine`s power happens below about 3,500 rpm; wind the engine out beyond that and it begins to feel breathless. If you`re accustomed to higher-revving gas engines, particularly those in smaller cars, the diesel can feel underpowered, but in truth, this car has no trouble keeping up with traffic when the engine is in the meaty part of the power band, which exists mostly within the engine`s 1,750-2,500 rpm torque peak. Also from a performance standpoint, the TDI produces an appealing, guttural sound under hard acceleration.

Volkswagen markets its latest TDI engines as Clean Diesels, and the exhaust it produces certainly smells that way. However, VW`s latest four-cylinder diesel technology cleans up the exhaust without the use of the urea-injection systems found in larger diesel engines. (The V6 TDI motor in the Touareg SUV uses urea injection, as do Mercedes` and BMW`s six-cylinder diesels.)

The Direct Shift Gearbox (DSG) in my car is as nice a piece as ever, offering smooth shifting in automatic mode, and one of the best manual modes to be found in any transmission this side of a true manual. Like the diesel engine, though, the DSG takes a bit of getting used to as well. For the most part, its operation is flawless, but it does display a tendency to lurch now and then as the car is slowed to a stop and the transmission downshifts.

The Jetta is proving a comfortable ride, with great front seats and decent space, and for a car whose powertrain focuses on fuel economy, it offers a far more entertaining drive in terms of handling compared to a hybrid. The suspension is tuned for comfort, but certainly not at the expense of roadholding.

Check back next month for another update on the performance of our long-term Jetta.

Connect with Autos.ca