I have had the same issues on my (early) 2010 TDI...
- Idling issue started a few months after I bought the car
- Fuel consumption at best average 5.8-6 l/100km
Initially thought the idling was due to using the cruise control, but after various "scenario tests" done by myself noticed that it had no influence.
The Polo has been to the dealers around 6 times, including once for the 15,000km service (where they also looked at the issue - see software). Dealers indicated that they:
- Updated the software to the latest version
- Checked all the filters
- Did all the pressure tests
- Technician even removed plugs and manually checked them
- Checked for leaks
The car would be fine for a week or two after it has been in, then the erratic idling would be back. Last time the car was in was 02/02/2011 (my son was two days old) when, the day before, I also had the Engine Management System as well as Catalytic Converter warning lights came on. This when the idling issue presented itself again on 30/01/2011.
Needless to say I am at my wits end. This because the erratic idling started this morning yet again, and then again this afternoon. Fuel consumption is slightly better, lower 5's, but still not on par. Especially since I drive very carefully (50-60 km/h urban, 110-120 km/h national roads) and keep the rev's mostly between 1,000-2,000 (obviously may go to 3,000 when I need to accelerate).
Made sound clips on my cell, which have been given to the dealer, they said they will send to the factory. I think they have done all they could with their immediate resources, we will have to see whether VWSA or the like will help.
This was my dream car - I always wanted a diesel, compact, light on fuel, better for the environment, power when I needed it. And of course, WCOTY. Doesn't help that we get ripped with car prices here in RSA and pay a premium for diesel cars - mine cost R210,000 (+/- GBP 18,100 or USD 29,400).
You can listen to the attached sound clip - just unzip. Happened this morning. Starts with erratic idling around 13 seconds.
P.S. the car only gets 50ppm diesel