I think (I'm not mechanic) on the old 1.9 TDI, the cetane boost additive is needed to improve engine performance, cleans injectors and lubricates fuel injection components.

For the 2.0 TDI (2009 and up), I do not think it is necessary and beneficial. For cons, I do not believe that it is bad for the engine. It's your choice.

FourCircle

 

I just signed up at fuelly, let's start tracking!!

 

Hey guys I picked up my certified pre-owned 2011 TDI back in January this year and I now have 31,000KM on it. Its running very smooth and I'm averaging 7.1/100 km or 39.7mpg

I have really been heavy with the gas pedal lately as the weather has been getting much nicer and I love the feel of that torque on acceleration, this cars got gobs of it!! And I'm doing about 80% in city or suburban roads in the GTA plus a 25 km drive to work. So I could probably do much better if I tried. The best tank iv'e done so far (in city) is 834 km at 53 liters of fuel which is 6.3L/100Km or 44.5 mpg.. not bad. I can't wait until summer for long road trips so i can aim for my 1000km + tank

Anyway Fourcircle is right i was using up more fuel in the winter and I was able to get better consumption numbers after I started plugging it in overnight.

Cheers and hope this helps.

 

I also have an 2012 A3 TDI which I got about 6 months ago. I've been averaging about 6.8 - 7.1 L / 100km over the course of this time, so I guess it is in line with some of the other drivers here. (On longer highway trips however (50km+) I average about 5.0 - 5.5 L / 100km)

One more thing to add to that is between the winter months, diesel fuel is usually less efficient because they have to mix it with a less combustible fuel to prevent diesel gelling (freezing). This usually happens between October - March / April. The colder the temperatures get, the more of this mixing they have to do. So when summer ramps up and they move away from mixing diesel, you should be able to get even better fuel mileage.

Hope that helps!

 

If boosting the cetane is your only goal with this additive then don't waste your time/money. The cetane value for diesel in Canada is plenty high enough. If you haven't found it yet, the best TDi resource I've ever found is tdiclub.com. The A3 section is small but tons of knowledge over there and most of what applies to the newer Jettas and Golfs will apply to your A3 as well.