Project TDI
Over the last couple of months we've lowered our '09 VW Jetta TDI using KW Variant 3 coilovers and added 19x8" BBS CH wheels with 235/35-19 Continental ContiSportContact3 tires. This month, we were focused on assessing these mods and preparing the car for its fuel economy challenge (see elsewhere in this issue).
With Justin snagging the TDI at every opportunity to visit his cosmetic specialist in preparation for gender transformation surgery - he's hoping to grow balls and become a man - I had to pry the keys from his lifeless fingers in order to try out the new mods.
Despite the minimal changes, the TDI has been transformed. The most obvious improvement is that it suddenly looks like something. Sitting squat over its motorsport wheels, our previously bland Jetta now attracts a few admiring comments. Apparently, one NorCal VW dealer wanted to know what we'd done and where he could get the parts to do the same. No wonder the motor industry's in such a mess
Other people have likened the car to a "baby Audi", while some thought it was a Passat. I guess the point here is that the car looks immensely more imposing and statuesque. It's no longer the ugly kid hiding in the corner.
So everybody seems to agree that lowering it and fitting big rims has worked wonders. But what affect have these parts had on its road manners?
Fortunately, the feedback is again positive. Despite the multi-adjustable KW V3 coilovers being slight overkill for a TDI road car, they aren't the rock-hard race units we were worried about. The ride is surprisingly supple - in a taut, racecar sort of way. The uncomfortable high-speed wallow of the stock suspension has gone, along with the battleship roll as you pitched it into corners.
The Jetta now rides firmly with superb body control. Even the 35-profile Conti rubber doesn't crash into potholes as you might expect.
Admittedly, we've got some of the very best European products on this car - KW suspension, BBS wheels, Continental tires - but it proves the old adage, "you get what you pay for"
Of course, there are compromises, albeit small ones. For starters, the front struts knock when cold. Apparently this is caused by the oil in the dampers being thicker until it warms up, but it causes some knocks from the front-end for about a mile. After that, the noise disappears.
We've also seen a negative affect on fuel economy. Ordinarily, we probably wouldn't monitor our fuel usage so closely, but we're fascinated by what we can squeeze out of the tank. To date we've seen between 38-45mpg on the freeway, depending on the weight of the individual driver's foot, with Sam's being the heaviest. However, Justin reported a 2-3% increase in fuel consumption after we'd fitted the new parts.
Similarly, where I was getting 26-28mpg on my daily commute using city streets, this has dropped to 24-26mpg with the new equipment.
Logically, this shouldn't be the suspension. In theory, a lower car is more aerodynamic. It shouldn't be the weight of the new wheels either. BBS claims the CH tips the scales at only 24 lb each, so that can't be the reason.
More likely, it's the increased turbulence from the wider wheels and tires, which are pushed out to the fender's edge. This will disrupt airflow along the side of the car, reducing fuel economy.
In addition, the new wheels mean our speedo is now reading 5% under, meaning 60mph is actually 63mph. Something to remember with a police car behind you!
It's a small price to pay, compared to the advantages of improved looks and cornering power, so we're sticking with the wider rubber. However, you may notice we resorted to the stock wheels to gain maximum mileage in the fuel economy run in this issue!
Once we've established the frugality of the Jetta's excellent 2.0 turbo-diesel engine, we aim to throw it all away with some engine mods to increase the phenomenal torque - more of that in a later issue.
Greg
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