[Lug_Nut]

My "duration of ownership" mpg for my first two Passats was over 50 mpg.
My red one went 135,111.7 miles on 2,573.76 gallons (all U.S. gallons, not those 20% bigger Imperial ones) for 52.5 mpg.
My black one went 118,394.0 on 2,316.668 gallons for 51.1 mpg. That one also got me a personal best of 82+ MPG during the 2003 Tour de Sol.
My next two were wagon versions. Although they didn't get as high mpg as the sedans, the bigger fuel tanks allowed 1400+ miles on one filling, on two separate occasions. If they didn't get 1000 miles per tank I was leaking fuel someplace. The best "single trip" mpg was 526 miles on 6.874 gallons for 76.5 mpg (Tour de Sol 2005). A total of 69,252 miles on 1417.57 gallons (48.85 mpg average).
That engine went in my second wagon. I just sold that one (for twice what I paid) and haven't yet tallied up the "lifetime" average, but I suspect it is a bit lower than in the first wagon. My job and commute had changed so I think it will be closer to mid 40's when I do total up that one.
<edit> I wanted to do it sooner or later, so I did it now. The second wagon I had for 33,599 miles and used 732.27 gallons for an average of 45.88 mpg. <end edit>
A 1986 Golf I had for 2058.2 miles, used 46.21 gallons for an average of 44.54 mpg. I sold it because it did so poorly. Sold it for more than I paid
I recently had a 1998 Jetta for 4118 miles and used 84.602 gallons for an average of 48.97. Sold that one for a profit, too.
The grand total of those is 362,532.9 miles on 7,171.08 gallons for an average of 50.55 mpg.
Oh, and these were all stock, with only VW supplied parts on them. No coroplastic, no fairings, no EOC, no P&G, no smoke 'n' mirror H2 generator, no acetone.

More emphasis on "eco", less on "modder".
Ciao.