the diesel numbers are in
I’ve now had my New Beetle TDI long enough to fill it with fuel twice. The first fill, after finally burning through the 3/4 of a tank that the vehicle came with, gave me a baseline to start measuring from. The second fill finally gave me my first glimpse into how efficient this particular vehicle is under my control.
During the second fill, 42.75L went into the tank. My trip odometer, having been reset after my first fill, read 868km. That, ladies and gentlemen, gives me the great pleasure of reporting that I managed to get 4.9L/100km out of my first measured tank of diesel. I did a happy dance all the way home!
I may be doing much better than that personally, in fact. With the Elantra I could personally average 6.0L/100km or better, but the tank average would always come out to 6.5L/100km. The reason was that my wife and I shared the vehicle (as we do now), and the tank average included her driving across the city to and from work a few times a week – just enough to bump up the tank average. If I assume that her influence on fuel economy is the same in this vehicle (adding 8% to my tank average fuel use) then my personal driving should be in the range of 4.5L/100km.
Based on my previous tank averages of 6.5L/100km on gasoline in the Elantra, and assuming equal fuel prices for gasoline and diesel (which isn’t true, diesel is cheaper), I’m saving approximately $1.50 per day in fuel costs.
I am pleased.
Andrew: Idea Hamster, P.Eng. 
You should post how much you’re saving, taking into account the cost of diesel, and multiplying it out to the net savings per year. That’ll get people noticing.
Glad to hear your experiment is paying off though. How’s the day-to-day running of the TDI? Have you worked out all the kinks (ie: no more power loss)?