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2009 Volkswagen Jetta TDI - Miser's Challenge

We wanted to see how miserly our Jetta TDI could be in a real-world driving situation against its leading rival

Greg Emmerson
Apr 1, 2009
Photographers: Sam Du, Sean Klingelhoefer
Eurp_0904_01_z+2009_volkswagen_jetta_tdi+challengers Photo 1/10   |   2009 Volkswagen Jetta TDI - Miser's Challenge

It was a genius, almost foolproof plan. Team up with sister magazine Super Street and test our '09 Jetta TDI against an'09 Toyota Prius to see which car was the most miserly in terms of fuel consumption over a pre-planned route. We'd then throw in modified gasoline examples of the VW GTI and Honda Civic for a real-world comparison, measuring the fuel used by all four cars.

And then the house of cards came tumbling down. The best laid plans and all that...

First of all, we must put our hands up. It's entirely our fault. We should never have thought the SS Brain Trust could actually follow our plan! It went wrong right at the start. First their project Civic wouldn't start, being quickly replaced by a stock vehicle. However, the real crusher was when the imports went off-route at the end of the challenge, and the Prius didn't record its final mileage or amount of fuel used!

They're all lovely fellows, but fortunately we had imagined the SSBT might encounter a few hiccups, so the plan made some allowances. As a result, our rainy day spent enduring epic Los Angeles traffic wasn't entirely wasted. In fact, we think you'll be shocked by what we discovered.

Eurp_0904_06_z+2009_volkswagen_jetta_tdi+side_view Photo 2/10   |   2009 Volkswagen Jetta TDI - Miser's Challenge

The idea for this story arose when VW invited us to drive and subsequently borrow its '09 Jetta TDI - a 140hp 2.0 turbo-diesel (et 1/09). Starting at only $21990 with free servicing for three years and eligibility for a $1300 federal tax credit, the car makes an attractive proposition. Throw in its EPA estimated fuel consumption of 30mpg city and 41mpg highway (manual trans), and you have a no-brainer.

During our first acquaintance, we man-aged to push the overall consumption to 45mpg using a mixture of roads, while some fuel economy experts had covered 9419 miles across the US using an average of 58mpg. So we wanted to see what we could really expect from the TDI on an extended drive over mixed roads.

As a result we chose a route that took us into the congested downtown area of Los Angeles. We'd then drive about 15 miles on traffic-clogged city streets to reach the I-10 freeway. This would be followed by about 35 miles on the freeway before dropping onto Pacific Coast Highway. We cruised out to one of our favorite canyon roads, finally returning home on city streets again.

Eurp_0904_08_z+2009_volkswagen_jetta_tdi+front_view Photo 3/10   |   2009 Volkswagen Jetta TDI - Miser's Challenge

TDI vs Prius
The brief was to have all four cars drive the same route at a similar pace to directly compare fuel used under these conditions.

The test began with a fill-up for all the cars, ensuring they were to the brim and a note of the odometer mileage was taken. We would then drive to the freeway. The rain was not only causing inevitable traffic jams, but the damp conditions forced us to use our wipers, heater and lights to maintain safe visibility. To be honest, we did occasionally switch off the engine at lights that stayed red longer than 15sec (as recommended), and we previously reverted to the stock wheels (see Our Cars in this issue), but we knew the Toyota Prius hybrid was in its element. By relying on its electric power, only using the gasoline engine to help with acceleration, the hybrid would be using almost no fuel under these conditions.

Our worst fears were realized when we stopped before entering the freeway to compare onboard computers. Admittedly, these aren't the most accurate gauge but, as it turned out, they would be our only indicator.

After fighting through downtown LA, the TDI had burnt an average of 27.2mpg at an average speed of 13mph. Yet the Prius returned 38.3mpg under the same conditions. This clearly shows the advantage of hybrid technology in busy cities.

Once on the freeway, an accident slowed our progress, again helping the Toyota. However, it soon cleared and we were cruising at a relaxed 60mph for more than 10 miles. After the freeway run, the TDI's onboard computer showed a frugal 47mpg, while the Prius recorded 44mpg. Using a light throttle, we expected the diesel to excel here, and given a longer run we could have got the number higher.

As we peeled off the freeway and merged onto PCH, the pace dropped slightly and there were irregular traffic lights. This allowed the Prius to catch up, so by the end of the highway section, the TDI returned 45.6mpg at an average of 37mph, while the Prius returned 46.5mpg.

The final numbers were recorded in the canyons. The initial uphill sections saw both cars return 17mpg as their engines fought against the incline. Once in the twisty sections of road, both cars returned about 21mpg. However, we're sure that the TDI could have squeezed out a lead over the hybrid if we'd traveled farther.

Eurp_0904_09_z+2009_volkswagen_jetta_tdi+gti_and_civic Photo 7/10   |   2009 Volkswagen Jetta TDI - Miser's Challenge

TDI vs GTI
As we mentioned earlier, our test also involved a gasoline-powered VW GTI and Honda Civic to give you an idea how cars possibly resembling your current transport compare against new, low-emissions vehicles.

The GTI was Sam's Project Silverstone. It boasts aftermarket software, exhaust manifold and system, front-mount, pulleys and intake on the 1.8T motor. The car has been lowered and wears 19x8" Hartmann wheels that inevitably create turbulence. There's also a 4Motion front spoiler to increase drag in favor of more stability. Furthermore, Sam's notoriously heavy-footed. Yet we asked him to accompany us to gauge how a typical tuner car would do. For the same reason, Sean Klingelhoefer from SS brought his '96 Civic 1.6L DOHC. While not as modified, it has been lowered and had a bike rack on the roof to disturb airflow.

Eurp_0904_05_z+2009_volkswagen_jetta_tdi+vs_gti Photo 8/10   |   2009 Volkswagen Jetta TDI - Miser's Challenge

After our 96-mile jaunt, our Jetta TDI returned an average of 41.74mpg. However, Sam's GTI only gave 15.95mpg. To be honest, it shocked us all. We never imagined our TDI would be almost three times better than a 1.8T. This was a real wake-up call to anybody driving a modified car. You really need to think about how you're driving and consider ways to improve your MPG before fuel prices inevitably rise again.

The Civic returned an average of 28.43mpg, but the driver somehow managed to miss the last 10 miles of city streets, so it's not directly comparable. However, the stock 1.6L is certainly better than our modified 1.8T. Yet it's at least 25% worse than our heavier Jetta.

Think MPG
What did our comparison teach us? Firstly, you don't have to be a rocket scientist to work on SS (OK, we'll stop busting their balls!).

Eurp_0904_04_z+2009_volkswagen_jetta_tdi+photo Photo 9/10   |   This is where the problems began - they couldn't even get one of the Civics started. Need we say more?

Actually, our test showed how the latest hybrid technology offers some genuine advantages for crowded city driving. But a modern turbo-diesel is just as good on freeways and highways. It's also just as good when pushed a little harder, making it a great alternative to the pious Prius if you don't regularly travel downtown.

The Prius costs a similar $22k and its EPA estimated figures are 48mpg city, 45mpg highway. It's clearly technically advanced and offers a short-term solution to long-term questions about global warming. However, our test has shown that the VW Jetta TDI is extremely frugal, packing a rush of mid-range torque. And any TDI driver can feel equally as self-righteous as Prius-owning tree-huggers.

One thing we should emphasize, is that you can maximize the fuel economy of any car. There are several websites offering tips, and common sense is a useful asset. Remember that the wider and longer the throttle is open, the more fuel you'll use. Simply putting it in a high gear isn't always the answer. If the gear is too high, you may have to press down farther on the throttle to accelerate the car, where changing down will actually allow the same acceleration from a smaller throttle opening. It's about using the gears wisely (assuming you have a manual transmission).

Eurp_0904_07_z+2009_volkswagen_jetta_tdi+front_view Photo 10/10   |   Any one of these cars can be driven economically or with a lead foot. It's often how you use it, not what you have...

You should also endeavor to maintain a constant speed at a small throttle opening. Some people accelerate and lift endlessly, closing up to the car in front, then backing off. Try to keep a good distance and set a constant speed at low revs.

Other things you can do: check your tire pressures, don't carry unnecessary weight, remove roof racks, etc when not in use, check your oil and service the car regularly to ensure its running efficiently. At the end of the day, it's up to us to preserve both the earth's resources and the money in our wallets. Lecture over, class dismissed.

You should also endeavor to maintain a constant speed at a small throttle opening. Some people accelerate and lift endlessly, closing up to the car in front, then backing off. Try to keep a good distance and set a constant speed at low revs.

Other things you can do: check your tire pressures, don't carry unnecessary weight, remove roof racks, etc when not in use, check your oil and service the car regularly to ensure its running efficiently. At the end of the day, it's up to us to preserve both the earth's resources and the money in our wallets. Lecture over, class dismissed.

By Greg Emmerson
1078 Articles

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